Add m-esr52 at 52.6.0

1 files changed, 1169 insertions, 0 deletions

diff --git a/layout/generic/nsColumnSetFrame.cpp b/layout/generic/nsColumnSetFrame.cpp
new file mode 100644
index 0000000000..ad36ba1a88
--- /dev/null
+++ b/layout/generic/nsColumnSetFrame.cpp
@@ -0,0 +1,1169 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* rendering object for css3 multi-column layout */
+
+#include "mozilla/Unused.h"
+#include "nsColumnSetFrame.h"
+#include "nsCSSRendering.h"
+#include "nsDisplayList.h"
+
+using namespace mozilla;
+using namespace mozilla::layout;
+
+/**
+ * Tracking issues:
+ *
+ * XXX cursor movement around the top and bottom of colums seems to make the editor
+ * lose the caret.
+ *
+ * XXX should we support CSS columns applied to table elements?
+ */
+nsContainerFrame*
+NS_NewColumnSetFrame(nsIPresShell* aPresShell, nsStyleContext* aContext, nsFrameState aStateFlags)
+{
+  nsColumnSetFrame* it = new (aPresShell) nsColumnSetFrame(aContext);
+  it->AddStateBits(aStateFlags | NS_BLOCK_MARGIN_ROOT);
+  return it;
+}
+
+NS_IMPL_FRAMEARENA_HELPERS(nsColumnSetFrame)
+
+nsColumnSetFrame::nsColumnSetFrame(nsStyleContext* aContext)
+  : nsContainerFrame(aContext), mLastBalanceBSize(NS_INTRINSICSIZE),
+    mLastFrameStatus(NS_FRAME_COMPLETE)
+{
+}
+
+nsIAtom*
+nsColumnSetFrame::GetType() const
+{
+  return nsGkAtoms::columnSetFrame;
+}
+
+static void
+PaintColumnRule(nsIFrame* aFrame, nsRenderingContext* aCtx,
+                const nsRect& aDirtyRect, nsPoint aPt)
+{
+  static_cast<nsColumnSetFrame*>(aFrame)->PaintColumnRule(aCtx, aDirtyRect, aPt);
+}
+
+void
+nsColumnSetFrame::PaintColumnRule(nsRenderingContext* aCtx,
+                                  const nsRect& aDirtyRect,
+                                  const nsPoint& aPt)
+{
+  nsIFrame* child = mFrames.FirstChild();
+  if (!child)
+    return;  // no columns
+
+  nsIFrame* nextSibling = child->GetNextSibling();
+  if (!nextSibling)
+    return;  // 1 column only - this means no gap to draw on
+
+  WritingMode wm = GetWritingMode();
+  bool isVertical = wm.IsVertical();
+  bool isRTL = !wm.IsBidiLTR();
+  const nsStyleColumn* colStyle = StyleColumn();
+
+  uint8_t ruleStyle;
+  // Per spec, inset => ridge and outset => groove
+  if (colStyle->mColumnRuleStyle == NS_STYLE_BORDER_STYLE_INSET)
+    ruleStyle = NS_STYLE_BORDER_STYLE_RIDGE;
+  else if (colStyle->mColumnRuleStyle == NS_STYLE_BORDER_STYLE_OUTSET)
+    ruleStyle = NS_STYLE_BORDER_STYLE_GROOVE;
+  else
+    ruleStyle = colStyle->mColumnRuleStyle;
+
+  nsPresContext* presContext = PresContext();
+  nscoord ruleWidth = colStyle->GetComputedColumnRuleWidth();
+  if (!ruleWidth)
+    return;
+
+  nscolor ruleColor =
+    GetVisitedDependentColor(eCSSProperty_column_rule_color);
+
+  // In order to re-use a large amount of code, we treat the column rule as a border.
+  // We create a new border style object and fill in all the details of the column rule as
+  // the left border. PaintBorder() does all the rendering for us, so we not
+  // only save an enormous amount of code but we'll support all the line styles that
+  // we support on borders!
+  nsStyleBorder border(presContext);
+  Sides skipSides;
+  if (isVertical) {
+    border.SetBorderWidth(NS_SIDE_TOP, ruleWidth);
+    border.SetBorderStyle(NS_SIDE_TOP, ruleStyle);
+    border.mBorderTopColor = StyleComplexColor::FromColor(ruleColor);
+    skipSides |= mozilla::eSideBitsLeftRight;
+    skipSides |= mozilla::eSideBitsBottom;
+  } else {
+    border.SetBorderWidth(NS_SIDE_LEFT, ruleWidth);
+    border.SetBorderStyle(NS_SIDE_LEFT, ruleStyle);
+    border.mBorderLeftColor = StyleComplexColor::FromColor(ruleColor);
+    skipSides |= mozilla::eSideBitsTopBottom;
+    skipSides |= mozilla::eSideBitsRight;
+  }
+
+  // Get our content rect as an absolute coordinate, not relative to
+  // our parent (which is what the X and Y normally is)
+  nsRect contentRect = GetContentRect() - GetRect().TopLeft() + aPt;
+  nsSize ruleSize = isVertical ? nsSize(contentRect.width, ruleWidth)
+                               : nsSize(ruleWidth, contentRect.height);
+
+  while (nextSibling) {
+    // The frame tree goes RTL in RTL.
+    // The |prevFrame| and |nextFrame| frames here are the visually preceding
+    // (left/above) and following (right/below) frames, not in logical writing-
+    // mode direction.
+    nsIFrame* prevFrame = isRTL ? nextSibling : child;
+    nsIFrame* nextFrame = isRTL ? child : nextSibling;
+
+    // Each child frame's position coordinates is actually relative to this
+    // nsColumnSetFrame.
+    // linePt will be at the top-left edge to paint the line.
+    nsPoint linePt;
+    if (isVertical) {
+      nscoord edgeOfPrev = prevFrame->GetRect().YMost() + aPt.y;
+      nscoord edgeOfNext = nextFrame->GetRect().Y() + aPt.y;
+      linePt = nsPoint(contentRect.x,
+                       (edgeOfPrev + edgeOfNext - ruleSize.height) / 2);
+    } else {
+      nscoord edgeOfPrev = prevFrame->GetRect().XMost() + aPt.x;
+      nscoord edgeOfNext = nextFrame->GetRect().X() + aPt.x;
+      linePt = nsPoint((edgeOfPrev + edgeOfNext - ruleSize.width) / 2,
+                       contentRect.y);
+    }
+
+    nsRect lineRect(linePt, ruleSize);
+
+    // Assert that we're not drawing a border-image here; if we were, we
+    // couldn't ignore the DrawResult that PaintBorderWithStyleBorder returns.
+    MOZ_ASSERT(border.mBorderImageSource.GetType() == eStyleImageType_Null);
+
+    Unused <<
+      nsCSSRendering::PaintBorderWithStyleBorder(presContext, *aCtx, this,
+                                                 aDirtyRect, lineRect, border,
+                                                 StyleContext(),
+                                                 PaintBorderFlags::SYNC_DECODE_IMAGES,
+                                                 skipSides);
+
+    child = nextSibling;
+    nextSibling = nextSibling->GetNextSibling();
+  }
+}
+
+static nscoord
+GetAvailableContentISize(const ReflowInput& aReflowInput)
+{
+  if (aReflowInput.AvailableISize() == NS_INTRINSICSIZE) {
+    return NS_INTRINSICSIZE;
+  }
+
+  WritingMode wm = aReflowInput.GetWritingMode();
+  nscoord borderPaddingISize =
+    aReflowInput.ComputedLogicalBorderPadding().IStartEnd(wm);
+  return std::max(0, aReflowInput.AvailableISize() - borderPaddingISize);
+}
+
+nscoord
+nsColumnSetFrame::GetAvailableContentBSize(const ReflowInput& aReflowInput)
+{
+  if (aReflowInput.AvailableBSize() == NS_INTRINSICSIZE) {
+    return NS_INTRINSICSIZE;
+  }
+
+  WritingMode wm = aReflowInput.GetWritingMode();
+  LogicalMargin bp = aReflowInput.ComputedLogicalBorderPadding();
+  bp.ApplySkipSides(GetLogicalSkipSides(&aReflowInput));
+  bp.BEnd(wm) = aReflowInput.ComputedLogicalBorderPadding().BEnd(wm);
+  return std::max(0, aReflowInput.AvailableBSize() - bp.BStartEnd(wm));
+}
+
+static nscoord
+GetColumnGap(nsColumnSetFrame*    aFrame,
+             const nsStyleColumn* aColStyle)
+{
+  if (eStyleUnit_Normal == aColStyle->mColumnGap.GetUnit())
+    return aFrame->StyleFont()->mFont.size;
+  if (eStyleUnit_Coord == aColStyle->mColumnGap.GetUnit()) {
+    nscoord colGap = aColStyle->mColumnGap.GetCoordValue();
+    NS_ASSERTION(colGap >= 0, "negative column gap");
+    return colGap;
+  }
+
+  NS_NOTREACHED("Unknown gap type");
+  return 0;
+}
+
+nsColumnSetFrame::ReflowConfig
+nsColumnSetFrame::ChooseColumnStrategy(const ReflowInput& aReflowInput,
+                                       bool aForceAuto = false,
+                                       nscoord aFeasibleBSize = NS_INTRINSICSIZE,
+                                       nscoord aInfeasibleBSize = 0)
+{
+  nscoord knownFeasibleBSize = aFeasibleBSize;
+  nscoord knownInfeasibleBSize = aInfeasibleBSize;
+
+  const nsStyleColumn* colStyle = StyleColumn();
+  nscoord availContentISize = GetAvailableContentISize(aReflowInput);
+  if (aReflowInput.ComputedISize() != NS_INTRINSICSIZE) {
+    availContentISize = aReflowInput.ComputedISize();
+  }
+
+  nscoord consumedBSize = GetConsumedBSize();
+
+  // The effective computed height is the height of the current continuation
+  // of the column set frame. This should be the same as the computed height
+  // if we have an unconstrained available height.
+  nscoord computedBSize = GetEffectiveComputedBSize(aReflowInput,
+                                                    consumedBSize);
+  nscoord colBSize = GetAvailableContentBSize(aReflowInput);
+
+  if (aReflowInput.ComputedBSize() != NS_INTRINSICSIZE) {
+    colBSize = aReflowInput.ComputedBSize();
+  } else if (aReflowInput.ComputedMaxBSize() != NS_INTRINSICSIZE) {
+    colBSize = std::min(colBSize, aReflowInput.ComputedMaxBSize());
+  }
+
+  nscoord colGap = GetColumnGap(this, colStyle);
+  int32_t numColumns = colStyle->mColumnCount;
+
+  // If column-fill is set to 'balance', then we want to balance the columns.
+  const bool isBalancing = colStyle->mColumnFill == NS_STYLE_COLUMN_FILL_BALANCE
+                           && !aForceAuto;
+  if (isBalancing) {
+    const uint32_t MAX_NESTED_COLUMN_BALANCING = 2;
+    uint32_t cnt = 0;
+    for (const ReflowInput* rs = aReflowInput.mParentReflowInput;
+         rs && cnt < MAX_NESTED_COLUMN_BALANCING; rs = rs->mParentReflowInput) {
+      if (rs->mFlags.mIsColumnBalancing) {
+        ++cnt;
+      }
+    }
+    if (cnt == MAX_NESTED_COLUMN_BALANCING) {
+      numColumns = 1;
+    }
+  }
+
+  nscoord colISize;
+  // In vertical writing-mode, "column-width" (inline size) will actually be
+  // physical height, but its CSS name is still column-width.
+  if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
+    colISize = colStyle->mColumnWidth.GetCoordValue();
+    NS_ASSERTION(colISize >= 0, "negative column width");
+    // Reduce column count if necessary to make columns fit in the
+    // available width. Compute max number of columns that fit in
+    // availContentISize, satisfying colGap*(maxColumns - 1) +
+    // colISize*maxColumns <= availContentISize
+    if (availContentISize != NS_INTRINSICSIZE && colGap + colISize > 0
+        && numColumns > 0) {
+      // This expression uses truncated rounding, which is what we
+      // want
+      int32_t maxColumns =
+        std::min(nscoord(nsStyleColumn::kMaxColumnCount),
+                 (availContentISize + colGap) / (colGap + colISize));
+      numColumns = std::max(1, std::min(numColumns, maxColumns));
+    }
+  } else if (numColumns > 0 && availContentISize != NS_INTRINSICSIZE) {
+    nscoord iSizeMinusGaps = availContentISize - colGap * (numColumns - 1);
+    colISize = iSizeMinusGaps / numColumns;
+  } else {
+    colISize = NS_INTRINSICSIZE;
+  }
+  // Take care of the situation where there's only one column but it's
+  // still too wide
+  colISize = std::max(1, std::min(colISize, availContentISize));
+
+  nscoord expectedISizeLeftOver = 0;
+
+  if (colISize != NS_INTRINSICSIZE && availContentISize != NS_INTRINSICSIZE) {
+    // distribute leftover space
+
+    // First, determine how many columns will be showing if the column
+    // count is auto
+    if (numColumns <= 0) {
+      // choose so that colGap*(nominalColumnCount - 1) +
+      // colISize*nominalColumnCount is nearly availContentISize
+      // make sure to round down
+      if (colGap + colISize > 0) {
+        numColumns = (availContentISize + colGap) / (colGap + colISize);
+        // The number of columns should never exceed kMaxColumnCount.
+        numColumns = std::min(nscoord(nsStyleColumn::kMaxColumnCount),
+                              numColumns);
+      }
+      if (numColumns <= 0) {
+        numColumns = 1;
+      }
+    }
+
+    // Compute extra space and divide it among the columns
+    nscoord extraSpace =
+      std::max(0, availContentISize - (colISize * numColumns +
+                                       colGap * (numColumns - 1)));
+    nscoord extraToColumns = extraSpace / numColumns;
+    colISize += extraToColumns;
+    expectedISizeLeftOver = extraSpace - (extraToColumns * numColumns);
+  }
+
+  if (isBalancing) {
+    if (numColumns <= 0) {
+      // Hmm, auto column count, column width or available width is unknown,
+      // and balancing is required. Let's just use one column then.
+      numColumns = 1;
+    }
+    colBSize = std::min(mLastBalanceBSize, colBSize);
+  } else {
+    // This is the case when the column-fill property is set to 'auto'.
+    // No balancing, so don't limit the column count
+    numColumns = INT32_MAX;
+
+    // XXX_jwir3: If a page's height is set to 0, we could continually
+    //            create continuations, resulting in an infinite loop, since
+    //            no progress is ever made. This is an issue with the spec
+    //            (css3-multicol, css3-page, and css3-break) that is
+    //            unresolved as of 27 Feb 2013. For the time being, we set this
+    //            to have a minimum of 1 css px. Once a resolution is made
+    //            on what minimum to have for a page height, we may need to
+    //            change this value to match the appropriate spec(s).
+    colBSize = std::max(colBSize, nsPresContext::CSSPixelsToAppUnits(1));
+  }
+
+#ifdef DEBUG_roc
+  printf("*** nsColumnSetFrame::ChooseColumnStrategy: numColumns=%d, colISize=%d,"
+         " expectedISizeLeftOver=%d, colBSize=%d, colGap=%d\n",
+         numColumns, colISize, expectedISizeLeftOver, colBSize, colGap);
+#endif
+  ReflowConfig config = { numColumns, colISize, expectedISizeLeftOver, colGap,
+                          colBSize, isBalancing, knownFeasibleBSize,
+                          knownInfeasibleBSize, computedBSize, consumedBSize };
+  return config;
+}
+
+bool
+nsColumnSetFrame::ReflowColumns(ReflowOutput& aDesiredSize,
+                                const ReflowInput& aReflowInput,
+                                nsReflowStatus& aReflowStatus,
+                                ReflowConfig& aConfig,
+                                bool aLastColumnUnbounded,
+                                nsCollapsingMargin* aCarriedOutBEndMargin,
+                                ColumnBalanceData& aColData)
+{
+  bool feasible = ReflowChildren(aDesiredSize, aReflowInput,
+                                 aReflowStatus, aConfig, aLastColumnUnbounded,
+                                 aCarriedOutBEndMargin, aColData);
+
+  if (aColData.mHasExcessBSize) {
+    aConfig = ChooseColumnStrategy(aReflowInput, true);
+
+    // We need to reflow our children again one last time, otherwise we might
+    // end up with a stale column height for some of our columns, since we
+    // bailed out of balancing.
+    feasible = ReflowChildren(aDesiredSize, aReflowInput, aReflowStatus,
+                              aConfig, aLastColumnUnbounded,
+                              aCarriedOutBEndMargin, aColData);
+  }
+
+  return feasible;
+}
+
+static void MoveChildTo(nsIFrame* aChild, LogicalPoint aOrigin,
+                        WritingMode aWM, const nsSize& aContainerSize)
+{
+  if (aChild->GetLogicalPosition(aWM, aContainerSize) == aOrigin) {
+    return;
+  }
+
+  aChild->SetPosition(aWM, aOrigin, aContainerSize);
+  nsContainerFrame::PlaceFrameView(aChild);
+}
+
+nscoord
+nsColumnSetFrame::GetMinISize(nsRenderingContext *aRenderingContext)
+{
+  nscoord iSize = 0;
+  DISPLAY_MIN_WIDTH(this, iSize);
+  if (mFrames.FirstChild()) {
+    iSize = mFrames.FirstChild()->GetMinISize(aRenderingContext);
+  }
+  const nsStyleColumn* colStyle = StyleColumn();
+  nscoord colISize;
+  if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
+    colISize = colStyle->mColumnWidth.GetCoordValue();
+    // As available width reduces to zero, we reduce our number of columns
+    // to one, and don't enforce the column width, so just return the min
+    // of the child's min-width with any specified column width.
+    iSize = std::min(iSize, colISize);
+  } else {
+    NS_ASSERTION(colStyle->mColumnCount > 0,
+                 "column-count and column-width can't both be auto");
+    // As available width reduces to zero, we still have mColumnCount columns,
+    // so multiply the child's min-width by the number of columns (n) and
+    // include n-1 column gaps.
+    colISize = iSize;
+    iSize *= colStyle->mColumnCount;
+    nscoord colGap = GetColumnGap(this, colStyle);
+    iSize += colGap * (colStyle->mColumnCount - 1);
+    // The multiplication above can make 'width' negative (integer overflow),
+    // so use std::max to protect against that.
+    iSize = std::max(iSize, colISize);
+  }
+  // XXX count forced column breaks here? Maybe we should return the child's
+  // min-width times the minimum number of columns.
+  return iSize;
+}
+
+nscoord
+nsColumnSetFrame::GetPrefISize(nsRenderingContext *aRenderingContext)
+{
+  // Our preferred width is our desired column width, if specified, otherwise
+  // the child's preferred width, times the number of columns, plus the width
+  // of any required column gaps
+  // XXX what about forced column breaks here?
+  nscoord result = 0;
+  DISPLAY_PREF_WIDTH(this, result);
+  const nsStyleColumn* colStyle = StyleColumn();
+  nscoord colGap = GetColumnGap(this, colStyle);
+
+  nscoord colISize;
+  if (colStyle->mColumnWidth.GetUnit() == eStyleUnit_Coord) {
+    colISize = colStyle->mColumnWidth.GetCoordValue();
+  } else if (mFrames.FirstChild()) {
+    colISize = mFrames.FirstChild()->GetPrefISize(aRenderingContext);
+  } else {
+    colISize = 0;
+  }
+
+  int32_t numColumns = colStyle->mColumnCount;
+  if (numColumns <= 0) {
+    // if column-count is auto, assume one column
+    numColumns = 1;
+  }
+
+  nscoord iSize = colISize * numColumns + colGap * (numColumns - 1);
+  // The multiplication above can make 'iSize' negative (integer overflow),
+  // so use std::max to protect against that.
+  result = std::max(iSize, colISize);
+  return result;
+}
+
+bool
+nsColumnSetFrame::ReflowChildren(ReflowOutput&     aDesiredSize,
+                                 const ReflowInput& aReflowInput,
+                                 nsReflowStatus&          aStatus,
+                                 const ReflowConfig&      aConfig,
+                                 bool                     aUnboundedLastColumn,
+                                 nsCollapsingMargin*      aCarriedOutBEndMargin,
+                                 ColumnBalanceData&       aColData)
+{
+  aColData.Reset();
+  bool allFit = true;
+  WritingMode wm = GetWritingMode();
+  bool isVertical = wm.IsVertical();
+  bool isRTL = !wm.IsBidiLTR();
+  bool shrinkingBSizeOnly = !NS_SUBTREE_DIRTY(this) &&
+    mLastBalanceBSize > aConfig.mColMaxBSize;
+
+#ifdef DEBUG_roc
+  printf("*** Doing column reflow pass: mLastBalanceBSize=%d, mColMaxBSize=%d, RTL=%d\n"
+         "    mBalanceColCount=%d, mColISize=%d, mColGap=%d\n",
+         mLastBalanceBSize, aConfig.mColMaxBSize, isRTL, aConfig.mBalanceColCount,
+         aConfig.mColISize, aConfig.mColGap);
+#endif
+
+  DrainOverflowColumns();
+
+  const bool colBSizeChanged = mLastBalanceBSize != aConfig.mColMaxBSize;
+
+  if (colBSizeChanged) {
+    mLastBalanceBSize = aConfig.mColMaxBSize;
+    // XXX Seems like this could fire if incremental reflow pushed the column set
+    // down so we reflow incrementally with a different available height.
+    // We need a way to do an incremental reflow and be sure availableHeight
+    // changes are taken account of! Right now I think block frames with absolute
+    // children might exit early.
+    //NS_ASSERTION(aKidReason != eReflowReason_Incremental,
+    //             "incremental reflow should not have changed the balance height");
+  }
+
+  // get our border and padding
+  LogicalMargin borderPadding = aReflowInput.ComputedLogicalBorderPadding();
+  borderPadding.ApplySkipSides(GetLogicalSkipSides(&aReflowInput));
+
+  nsRect contentRect(0, 0, 0, 0);
+  nsOverflowAreas overflowRects;
+
+  nsIFrame* child = mFrames.FirstChild();
+  LogicalPoint childOrigin(wm, borderPadding.IStart(wm),
+                           borderPadding.BStart(wm));
+  // In vertical-rl mode, columns will not be correctly placed if the
+  // reflowInput's ComputedWidth() is UNCONSTRAINED (in which case we'll get
+  // a containerSize.width of zero here). In that case, the column positions
+  // will be adjusted later, after our correct contentSize is known.
+  nsSize containerSize = aReflowInput.ComputedSizeAsContainerIfConstrained();
+
+  // For RTL, since the columns might not fill the frame exactly, we
+  // need to account for the slop. Otherwise we'll waste time moving the
+  // columns by some tiny amount
+
+  // XXX when all of layout is converted to logical coordinates, we
+  //     probably won't need to do this hack any more. For now, we
+  //     confine it to the legacy horizontal-rl case
+  if (!isVertical && isRTL) {
+    nscoord availISize = aReflowInput.AvailableISize();
+    if (aReflowInput.ComputedISize() != NS_INTRINSICSIZE) {
+      availISize = aReflowInput.ComputedISize();
+    }
+    if (availISize != NS_INTRINSICSIZE) {
+      childOrigin.I(wm) = containerSize.width - borderPadding.Left(wm) -
+                          availISize;
+#ifdef DEBUG_roc
+      printf("*** childOrigin.iCoord = %d\n", childOrigin.I(wm));
+#endif
+    }
+  }
+
+  int columnCount = 0;
+  int contentBEnd = 0;
+  bool reflowNext = false;
+
+  while (child) {
+    // Try to skip reflowing the child. We can't skip if the child is dirty. We also can't
+    // skip if the next column is dirty, because the next column's first line(s)
+    // might be pullable back to this column. We can't skip if it's the last child
+    // because we need to obtain the bottom margin. We can't skip
+    // if this is the last column and we're supposed to assign unbounded
+    // height to it, because that could change the available height from
+    // the last time we reflowed it and we should try to pull all the
+    // content from its next sibling. (Note that it might be the last
+    // column, but not be the last child because the desired number of columns
+    // has changed.)
+    bool skipIncremental = !aReflowInput.ShouldReflowAllKids()
+      && !NS_SUBTREE_DIRTY(child)
+      && child->GetNextSibling()
+      && !(aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1)
+      && !NS_SUBTREE_DIRTY(child->GetNextSibling());
+    // If we need to pull up content from the prev-in-flow then this is not just
+    // a height shrink. The prev in flow will have set the dirty bit.
+    // Check the overflow rect YMost instead of just the child's content height. The child
+    // may have overflowing content that cares about the available height boundary.
+    // (It may also have overflowing content that doesn't care about the available height
+    // boundary, but if so, too bad, this optimization is defeated.)
+    // We want scrollable overflow here since this is a calculation that
+    // affects layout.
+    bool skipResizeBSizeShrink = false;
+    if (shrinkingBSizeOnly) {
+      switch (wm.GetBlockDir()) {
+      case WritingMode::eBlockTB:
+        if (child->GetScrollableOverflowRect().YMost() <= aConfig.mColMaxBSize) {
+          skipResizeBSizeShrink = true;
+        }
+        break;
+      case WritingMode::eBlockLR:
+        if (child->GetScrollableOverflowRect().XMost() <= aConfig.mColMaxBSize) {
+          skipResizeBSizeShrink = true;
+        }
+        break;
+      case WritingMode::eBlockRL:
+        // XXX not sure how to handle this, so for now just don't attempt
+        // the optimization
+        break;
+      default:
+        NS_NOTREACHED("unknown block direction");
+        break;
+      }
+    }
+
+    nscoord childContentBEnd = 0;
+    if (!reflowNext && (skipIncremental || skipResizeBSizeShrink)) {
+      // This child does not need to be reflowed, but we may need to move it
+      MoveChildTo(child, childOrigin, wm, containerSize);
+
+      // If this is the last frame then make sure we get the right status
+      nsIFrame* kidNext = child->GetNextSibling();
+      if (kidNext) {
+        aStatus = (kidNext->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)
+                  ? NS_FRAME_OVERFLOW_INCOMPLETE
+                  : NS_FRAME_NOT_COMPLETE;
+      } else {
+        aStatus = mLastFrameStatus;
+      }
+      childContentBEnd = nsLayoutUtils::CalculateContentBEnd(wm, child);
+#ifdef DEBUG_roc
+      printf("*** Skipping child #%d %p (incremental %d, resize block-size shrink %d): status = %d\n",
+             columnCount, (void*)child, skipIncremental, skipResizeBSizeShrink, aStatus);
+#endif
+    } else {
+      LogicalSize availSize(wm, aConfig.mColISize, aConfig.mColMaxBSize);
+      if (aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1) {
+        availSize.BSize(wm) = GetAvailableContentBSize(aReflowInput);
+      }
+
+      LogicalSize computedSize = aReflowInput.ComputedSize(wm);
+
+      if (reflowNext)
+        child->AddStateBits(NS_FRAME_IS_DIRTY);
+
+      LogicalSize kidCBSize(wm, availSize.ISize(wm), computedSize.BSize(wm));
+      ReflowInput kidReflowInput(PresContext(), aReflowInput, child,
+                                       availSize, &kidCBSize);
+      kidReflowInput.mFlags.mIsTopOfPage = true;
+      kidReflowInput.mFlags.mTableIsSplittable = false;
+      kidReflowInput.mFlags.mIsColumnBalancing = aConfig.mBalanceColCount < INT32_MAX;
+
+      // We need to reflow any float placeholders, even if our column height
+      // hasn't changed.
+      kidReflowInput.mFlags.mMustReflowPlaceholders = !colBSizeChanged;
+
+#ifdef DEBUG_roc
+      printf("*** Reflowing child #%d %p: availHeight=%d\n",
+             columnCount, (void*)child,availSize.BSize(wm));
+#endif
+
+      // Note if the column's next in flow is not being changed by this incremental reflow.
+      // This may allow the current column to avoid trying to pull lines from the next column.
+      if (child->GetNextSibling() &&
+          !(GetStateBits() & NS_FRAME_IS_DIRTY) &&
+        !(child->GetNextSibling()->GetStateBits() & NS_FRAME_IS_DIRTY)) {
+        kidReflowInput.mFlags.mNextInFlowUntouched = true;
+      }
+
+      ReflowOutput kidDesiredSize(wm, aDesiredSize.mFlags);
+
+      // XXX it would be cool to consult the float manager for the
+      // previous block to figure out the region of floats from the
+      // previous column that extend into this column, and subtract
+      // that region from the new float manager.  So you could stick a
+      // really big float in the first column and text in following
+      // columns would flow around it.
+
+      // Reflow the frame
+      LogicalPoint origin(wm,
+                          childOrigin.I(wm) +
+                          kidReflowInput.ComputedLogicalMargin().IStart(wm),
+                          childOrigin.B(wm) +
+                          kidReflowInput.ComputedLogicalMargin().BStart(wm));
+      ReflowChild(child, PresContext(), kidDesiredSize, kidReflowInput,
+                  wm, origin, containerSize, 0, aStatus);
+
+      reflowNext = (aStatus & NS_FRAME_REFLOW_NEXTINFLOW) != 0;
+
+#ifdef DEBUG_roc
+      printf("*** Reflowed child #%d %p: status = %d, desiredSize=%d,%d CarriedOutBEndMargin=%d\n",
+             columnCount, (void*)child, aStatus, kidDesiredSize.Width(), kidDesiredSize.Height(),
+             kidDesiredSize.mCarriedOutBEndMargin.get());
+#endif
+
+      NS_FRAME_TRACE_REFLOW_OUT("Column::Reflow", aStatus);
+
+      *aCarriedOutBEndMargin = kidDesiredSize.mCarriedOutBEndMargin;
+
+      FinishReflowChild(child, PresContext(), kidDesiredSize,
+                        &kidReflowInput, wm, childOrigin, containerSize, 0);
+
+      childContentBEnd = nsLayoutUtils::CalculateContentBEnd(wm, child);
+      if (childContentBEnd > aConfig.mColMaxBSize) {
+        allFit = false;
+      }
+      if (childContentBEnd > availSize.BSize(wm)) {
+        aColData.mMaxOverflowingBSize = std::max(childContentBEnd,
+            aColData.mMaxOverflowingBSize);
+      }
+    }
+
+    contentRect.UnionRect(contentRect, child->GetRect());
+
+    ConsiderChildOverflow(overflowRects, child);
+    contentBEnd = std::max(contentBEnd, childContentBEnd);
+    aColData.mLastBSize = childContentBEnd;
+    aColData.mSumBSize += childContentBEnd;
+
+    // Build a continuation column if necessary
+    nsIFrame* kidNextInFlow = child->GetNextInFlow();
+
+    if (NS_FRAME_IS_FULLY_COMPLETE(aStatus) && !NS_FRAME_IS_TRUNCATED(aStatus)) {
+      NS_ASSERTION(!kidNextInFlow, "next in flow should have been deleted");
+      child = nullptr;
+      break;
+    } else {
+      ++columnCount;
+      // Make sure that the column has a next-in-flow. If not, we must
+      // create one to hold the overflowing stuff, even if we're just
+      // going to put it on our overflow list and let *our*
+      // next in flow handle it.
+      if (!kidNextInFlow) {
+        NS_ASSERTION(aStatus & NS_FRAME_REFLOW_NEXTINFLOW,
+                     "We have to create a continuation, but the block doesn't want us to reflow it?");
+
+        // We need to create a continuing column
+        kidNextInFlow = CreateNextInFlow(child);
+      }
+
+      // Make sure we reflow a next-in-flow when it switches between being
+      // normal or overflow container
+      if (NS_FRAME_OVERFLOW_IS_INCOMPLETE(aStatus)) {
+        if (!(kidNextInFlow->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)) {
+          aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
+          reflowNext = true;
+          kidNextInFlow->AddStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
+        }
+      }
+      else if (kidNextInFlow->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER) {
+        aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
+        reflowNext = true;
+        kidNextInFlow->RemoveStateBits(NS_FRAME_IS_OVERFLOW_CONTAINER);
+      }
+
+      if ((contentBEnd > aReflowInput.ComputedMaxBSize() ||
+           contentBEnd > aReflowInput.ComputedBSize()) &&
+           aConfig.mBalanceColCount < INT32_MAX) {
+        // We overflowed vertically, but have not exceeded the number of
+        // columns. We're going to go into overflow columns now, so balancing
+        // no longer applies.
+        aColData.mHasExcessBSize = true;
+      }
+
+      if (columnCount >= aConfig.mBalanceColCount) {
+        // No more columns allowed here. Stop.
+        aStatus |= NS_FRAME_REFLOW_NEXTINFLOW;
+        kidNextInFlow->AddStateBits(NS_FRAME_IS_DIRTY);
+        // Move any of our leftover columns to our overflow list. Our
+        // next-in-flow will eventually pick them up.
+        const nsFrameList& continuationColumns = mFrames.RemoveFramesAfter(child);
+        if (continuationColumns.NotEmpty()) {
+          SetOverflowFrames(continuationColumns);
+        }
+        child = nullptr;
+        break;
+      }
+    }
+
+    if (PresContext()->HasPendingInterrupt()) {
+      // Stop the loop now while |child| still points to the frame that bailed
+      // out.  We could keep going here and condition a bunch of the code in
+      // this loop on whether there's an interrupt, or even just keep going and
+      // trying to reflow the blocks (even though we know they'll interrupt
+      // right after their first line), but stopping now is conceptually the
+      // simplest (and probably fastest) thing.
+      break;
+    }
+
+    // Advance to the next column
+    child = child->GetNextSibling();
+
+    if (child) {
+      childOrigin.I(wm) += aConfig.mColISize + aConfig.mColGap;
+
+#ifdef DEBUG_roc
+      printf("*** NEXT CHILD ORIGIN.icoord = %d\n", childOrigin.I(wm));
+#endif
+    }
+  }
+
+  if (PresContext()->CheckForInterrupt(this) &&
+      (GetStateBits() & NS_FRAME_IS_DIRTY)) {
+    // Mark all our kids starting with |child| dirty
+
+    // Note that this is a CheckForInterrupt call, not a HasPendingInterrupt,
+    // because we might have interrupted while reflowing |child|, and since
+    // we're about to add a dirty bit to |child| we need to make sure that
+    // |this| is scheduled to have dirty bits marked on it and its ancestors.
+    // Otherwise, when we go to mark dirty bits on |child|'s ancestors we'll
+    // bail out immediately, since it'll already have a dirty bit.
+    for (; child; child = child->GetNextSibling()) {
+      child->AddStateBits(NS_FRAME_IS_DIRTY);
+    }
+  }
+
+  aColData.mMaxBSize = contentBEnd;
+  LogicalSize contentSize = LogicalSize(wm, contentRect.Size());
+  contentSize.BSize(wm) = std::max(contentSize.BSize(wm), contentBEnd);
+  mLastFrameStatus = aStatus;
+
+  // Apply computed and min/max values
+  if (aConfig.mComputedBSize != NS_INTRINSICSIZE) {
+    if (aReflowInput.AvailableBSize() != NS_INTRINSICSIZE) {
+      contentSize.BSize(wm) = std::min(contentSize.BSize(wm),
+                                       aConfig.mComputedBSize);
+    } else {
+      contentSize.BSize(wm) = aConfig.mComputedBSize;
+    }
+  } else {
+    // We add the "consumed" block-size back in so that we're applying
+    // constraints to the correct bSize value, then subtract it again
+    // after we've finished with the min/max calculation. This prevents us from
+    // having a last continuation that is smaller than the min bSize. but which
+    // has prev-in-flows, trigger a larger bSize than actually required.
+    contentSize.BSize(wm) =
+      aReflowInput.ApplyMinMaxBSize(contentSize.BSize(wm),
+                                    aConfig.mConsumedBSize);
+  }
+  if (aReflowInput.ComputedISize() != NS_INTRINSICSIZE) {
+    contentSize.ISize(wm) = aReflowInput.ComputedISize();
+  } else {
+    contentSize.ISize(wm) =
+      aReflowInput.ApplyMinMaxISize(contentSize.ISize(wm));
+  }
+
+  contentSize.ISize(wm) += borderPadding.IStartEnd(wm);
+  contentSize.BSize(wm) += borderPadding.BStartEnd(wm);
+  aDesiredSize.SetSize(wm, contentSize);
+  aDesiredSize.mOverflowAreas = overflowRects;
+  aDesiredSize.UnionOverflowAreasWithDesiredBounds();
+
+  // In vertical-rl mode, make a second pass if necessary to reposition the
+  // columns with the correct container width. (In other writing modes,
+  // correct containerSize was not required for column positioning so we don't
+  // need this fixup.)
+  if (wm.IsVerticalRL() && containerSize.width != contentSize.Width(wm)) {
+    const nsSize finalContainerSize = aDesiredSize.PhysicalSize();
+    for (nsIFrame* child : mFrames) {
+      // Get the logical position as set previously using a provisional or
+      // dummy containerSize, and reset with the correct container size.
+      child->SetPosition(wm, child->GetLogicalPosition(wm, containerSize),
+                         finalContainerSize);
+    }
+  }
+
+#ifdef DEBUG_roc
+  printf("*** DONE PASS feasible=%d\n", allFit && NS_FRAME_IS_FULLY_COMPLETE(aStatus)
+         && !NS_FRAME_IS_TRUNCATED(aStatus));
+#endif
+  return allFit && NS_FRAME_IS_FULLY_COMPLETE(aStatus)
+    && !NS_FRAME_IS_TRUNCATED(aStatus);
+}
+
+void
+nsColumnSetFrame::DrainOverflowColumns()
+{
+  // First grab the prev-in-flows overflows and reparent them to this
+  // frame.
+  nsPresContext* presContext = PresContext();
+  nsColumnSetFrame* prev = static_cast<nsColumnSetFrame*>(GetPrevInFlow());
+  if (prev) {
+    AutoFrameListPtr overflows(presContext, prev->StealOverflowFrames());
+    if (overflows) {
+      nsContainerFrame::ReparentFrameViewList(*overflows, prev, this);
+
+      mFrames.InsertFrames(this, nullptr, *overflows);
+    }
+  }
+  
+  // Now pull back our own overflows and append them to our children.
+  // We don't need to reparent them since we're already their parent.
+  AutoFrameListPtr overflows(presContext, StealOverflowFrames());
+  if (overflows) {
+    // We're already the parent for these frames, so no need to set
+    // their parent again.
+    mFrames.AppendFrames(nullptr, *overflows);
+  }
+}
+
+void
+nsColumnSetFrame::FindBestBalanceBSize(const ReflowInput& aReflowInput,
+                                       nsPresContext* aPresContext,
+                                       ReflowConfig& aConfig,
+                                       ColumnBalanceData& aColData,
+                                       ReflowOutput& aDesiredSize,
+                                       nsCollapsingMargin& aOutMargin,
+                                       bool& aUnboundedLastColumn,
+                                       bool& aRunWasFeasible,
+                                       nsReflowStatus& aStatus)
+{
+  bool feasible = aRunWasFeasible;
+
+  nsMargin bp = aReflowInput.ComputedPhysicalBorderPadding();
+  bp.ApplySkipSides(GetSkipSides());
+  bp.bottom = aReflowInput.ComputedPhysicalBorderPadding().bottom;
+
+  nscoord availableContentBSize =
+    GetAvailableContentBSize(aReflowInput);
+
+  // Termination of the algorithm below is guaranteed because
+  // aConfig.knownFeasibleBSize - aConfig.knownInfeasibleBSize decreases in every
+  // iteration.
+
+  // We set this flag when we detect that we may contain a frame
+  // that can break anywhere (thus foiling the linear decrease-by-one
+  // search)
+  bool maybeContinuousBreakingDetected = false;
+
+  while (!aPresContext->HasPendingInterrupt()) {
+    nscoord lastKnownFeasibleBSize = aConfig.mKnownFeasibleBSize;
+
+    // Record what we learned from the last reflow
+    if (feasible) {
+      // maxBSize is feasible. Also, mLastBalanceBSize is feasible.
+      aConfig.mKnownFeasibleBSize = std::min(aConfig.mKnownFeasibleBSize,
+                                              aColData.mMaxBSize);
+      aConfig.mKnownFeasibleBSize = std::min(aConfig.mKnownFeasibleBSize,
+                                              mLastBalanceBSize);
+
+      // Furthermore, no height less than the height of the last
+      // column can ever be feasible. (We might be able to reduce the
+      // height of a non-last column by moving content to a later column,
+      // but we can't do that with the last column.)
+      if (mFrames.GetLength() == aConfig.mBalanceColCount) {
+        aConfig.mKnownInfeasibleBSize = std::max(aConfig.mKnownInfeasibleBSize,
+                                       aColData.mLastBSize - 1);
+      }
+    } else {
+      aConfig.mKnownInfeasibleBSize = std::max(aConfig.mKnownInfeasibleBSize,
+                                                mLastBalanceBSize);
+      // If a column didn't fit in its available height, then its current
+      // height must be the minimum height for unbreakable content in
+      // the column, and therefore no smaller height can be feasible.
+      aConfig.mKnownInfeasibleBSize = std::max(aConfig.mKnownInfeasibleBSize,
+                                         aColData.mMaxOverflowingBSize - 1);
+
+      if (aUnboundedLastColumn) {
+        // The last column is unbounded, so all content got reflowed, so the
+        // mColMaxBSize is feasible.
+        aConfig.mKnownFeasibleBSize = std::min(aConfig.mKnownFeasibleBSize,
+                                                aColData.mMaxBSize);
+      }
+    }
+
+#ifdef DEBUG_roc
+    printf("*** nsColumnSetFrame::Reflow balancing knownInfeasible=%d knownFeasible=%d\n",
+           aConfig.mKnownInfeasibleBSize, aConfig.mKnownFeasibleBSize);
+#endif
+
+
+    if (aConfig.mKnownInfeasibleBSize >= aConfig.mKnownFeasibleBSize - 1) {
+      // aConfig.mKnownFeasibleBSize is where we want to be
+      break;
+    }
+
+    if (aConfig.mKnownInfeasibleBSize >= availableContentBSize) {
+      break;
+    }
+
+    if (lastKnownFeasibleBSize - aConfig.mKnownFeasibleBSize == 1) {
+      // We decreased the feasible height by one twip only. This could
+      // indicate that there is a continuously breakable child frame
+      // that we are crawling through.
+      maybeContinuousBreakingDetected = true;
+    }
+
+    nscoord nextGuess = (aConfig.mKnownFeasibleBSize + aConfig.mKnownInfeasibleBSize)/2;
+    // The constant of 600 twips is arbitrary. It's about two line-heights.
+    if (aConfig.mKnownFeasibleBSize - nextGuess < 600 &&
+        !maybeContinuousBreakingDetected) {
+      // We're close to our target, so just try shrinking just the
+      // minimum amount that will cause one of our columns to break
+      // differently.
+      nextGuess = aConfig.mKnownFeasibleBSize - 1;
+    } else if (aUnboundedLastColumn) {
+      // Make a guess by dividing that into N columns. Add some slop
+      // to try to make it on the feasible side.  The constant of
+      // 600 twips is arbitrary. It's about two line-heights.
+      nextGuess = aColData.mSumBSize/aConfig.mBalanceColCount + 600;
+      // Sanitize it
+      nextGuess = clamped(nextGuess, aConfig.mKnownInfeasibleBSize + 1,
+                                     aConfig.mKnownFeasibleBSize - 1);
+    } else if (aConfig.mKnownFeasibleBSize == NS_INTRINSICSIZE) {
+      // This can happen when we had a next-in-flow so we didn't
+      // want to do an unbounded height measuring step. Let's just increase
+      // from the infeasible height by some reasonable amount.
+      nextGuess = aConfig.mKnownInfeasibleBSize*2 + 600;
+    }
+    // Don't bother guessing more than our height constraint.
+    nextGuess = std::min(availableContentBSize, nextGuess);
+
+#ifdef DEBUG_roc
+    printf("*** nsColumnSetFrame::Reflow balancing choosing next guess=%d\n", nextGuess);
+#endif
+
+    aConfig.mColMaxBSize = nextGuess;
+
+    aUnboundedLastColumn = false;
+    AddStateBits(NS_FRAME_IS_DIRTY);
+    feasible = ReflowColumns(aDesiredSize, aReflowInput, aStatus, aConfig, false,
+                             &aOutMargin, aColData);
+
+    if (!aConfig.mIsBalancing) {
+      // Looks like we had excess height when balancing, so we gave up on
+      // trying to balance.
+      break;
+    }
+  }
+
+  if (aConfig.mIsBalancing && !feasible &&
+      !aPresContext->HasPendingInterrupt()) {
+    // We may need to reflow one more time at the feasible height to
+    // get a valid layout.
+    bool skip = false;
+    if (aConfig.mKnownInfeasibleBSize >= availableContentBSize) {
+      aConfig.mColMaxBSize = availableContentBSize;
+      if (mLastBalanceBSize == availableContentBSize) {
+        skip = true;
+      }
+    } else {
+      aConfig.mColMaxBSize = aConfig.mKnownFeasibleBSize;
+    }
+    if (!skip) {
+      // If our height is unconstrained, make sure that the last column is
+      // allowed to have arbitrary height here, even though we were balancing.
+      // Otherwise we'd have to split, and it's not clear what we'd do with
+      // that.
+      AddStateBits(NS_FRAME_IS_DIRTY);
+      feasible = ReflowColumns(aDesiredSize, aReflowInput, aStatus, aConfig,
+                               availableContentBSize == NS_UNCONSTRAINEDSIZE,
+                               &aOutMargin, aColData);
+    }
+  }
+
+  aRunWasFeasible = feasible;
+}
+
+void
+nsColumnSetFrame::Reflow(nsPresContext*           aPresContext,
+                         ReflowOutput&     aDesiredSize,
+                         const ReflowInput& aReflowInput,
+                         nsReflowStatus&          aStatus)
+{
+  MarkInReflow();
+  // Don't support interruption in columns
+  nsPresContext::InterruptPreventer noInterrupts(aPresContext);
+
+  DO_GLOBAL_REFLOW_COUNT("nsColumnSetFrame");
+  DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus);
+
+  // Initialize OUT parameter
+  aStatus = NS_FRAME_COMPLETE;
+
+  // Our children depend on our block-size if we have a fixed block-size.
+  if (aReflowInput.ComputedBSize() != NS_AUTOHEIGHT) {
+    AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+  } else {
+    RemoveStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE);
+  }
+
+#ifdef DEBUG
+  nsFrameList::Enumerator oc(GetChildList(kOverflowContainersList));
+  for (; !oc.AtEnd(); oc.Next()) {
+    MOZ_ASSERT(!IS_TRUE_OVERFLOW_CONTAINER(oc.get()));
+  }
+  nsFrameList::Enumerator eoc(GetChildList(kExcessOverflowContainersList));
+  for (; !eoc.AtEnd(); eoc.Next()) {
+    MOZ_ASSERT(!IS_TRUE_OVERFLOW_CONTAINER(eoc.get()));
+  }
+#endif
+
+  nsOverflowAreas ocBounds;
+  nsReflowStatus ocStatus = NS_FRAME_COMPLETE;
+  if (GetPrevInFlow()) {
+    ReflowOverflowContainerChildren(aPresContext, aReflowInput, ocBounds, 0,
+                                    ocStatus);
+  }
+
+  //------------ Handle Incremental Reflow -----------------
+
+  // If inline size is unconstrained, set aForceAuto to true to allow
+  // the columns to expand in the inline direction. (This typically
+  // happens in orthogonal flows where the inline direction is the
+  // container's block direction).
+  ReflowConfig config =
+    ChooseColumnStrategy(aReflowInput,
+                         aReflowInput.ComputedISize() == NS_UNCONSTRAINEDSIZE);
+
+  // If balancing, then we allow the last column to grow to unbounded
+  // height during the first reflow. This gives us a way to estimate
+  // what the average column height should be, because we can measure
+  // the heights of all the columns and sum them up. But don't do this
+  // if we have a next in flow because we don't want to suck all its
+  // content back here and then have to push it out again!
+  nsIFrame* nextInFlow = GetNextInFlow();
+  bool unboundedLastColumn = config.mIsBalancing && !nextInFlow;
+  nsCollapsingMargin carriedOutBottomMargin;
+  ColumnBalanceData colData;
+  colData.mHasExcessBSize = false;
+
+  bool feasible = ReflowColumns(aDesiredSize, aReflowInput, aStatus, config,
+                                unboundedLastColumn, &carriedOutBottomMargin,
+                                colData);
+
+  // If we're not balancing, then we're already done, since we should have
+  // reflown all of our children, and there is no need for a binary search to
+  // determine proper column height.
+  if (config.mIsBalancing && !aPresContext->HasPendingInterrupt()) {
+    FindBestBalanceBSize(aReflowInput, aPresContext, config, colData,
+                          aDesiredSize, carriedOutBottomMargin,
+                          unboundedLastColumn, feasible, aStatus);
+  }
+
+  if (aPresContext->HasPendingInterrupt() &&
+      aReflowInput.AvailableBSize() == NS_UNCONSTRAINEDSIZE) {
+    // In this situation, we might be lying about our reflow status, because
+    // our last kid (the one that got interrupted) was incomplete.  Fix that.
+    aStatus = NS_FRAME_COMPLETE;
+  }
+
+  NS_ASSERTION(NS_FRAME_IS_FULLY_COMPLETE(aStatus) ||
+               aReflowInput.AvailableBSize() != NS_UNCONSTRAINEDSIZE,
+               "Column set should be complete if the available block-size is unconstrained");
+
+  // Merge overflow container bounds and status.
+  aDesiredSize.mOverflowAreas.UnionWith(ocBounds);
+  NS_MergeReflowStatusInto(&aStatus, ocStatus);
+
+  FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize, aReflowInput, aStatus, false);
+
+  aDesiredSize.mCarriedOutBEndMargin = carriedOutBottomMargin;
+
+  NS_FRAME_SET_TRUNCATION(aStatus, aReflowInput, aDesiredSize);
+}
+
+void
+nsColumnSetFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                   const nsRect&           aDirtyRect,
+                                   const nsDisplayListSet& aLists)
+{
+  DisplayBorderBackgroundOutline(aBuilder, aLists);
+
+  if (IsVisibleForPainting(aBuilder)) {
+    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
+      nsDisplayGenericOverflow(aBuilder, this, ::PaintColumnRule, "ColumnRule",
+                               nsDisplayItem::TYPE_COLUMN_RULE));
+  }
+
+  // Our children won't have backgrounds so it doesn't matter where we put them.
+  for (nsFrameList::Enumerator e(mFrames); !e.AtEnd(); e.Next()) {
+    BuildDisplayListForChild(aBuilder, e.get(), aDirtyRect, aLists);
+  }
+}
+
+#ifdef DEBUG
+void
+nsColumnSetFrame::SetInitialChildList(ChildListID     aListID,
+                                      nsFrameList&    aChildList)
+{
+  MOZ_ASSERT(aListID != kPrincipalList || aChildList.OnlyChild(),
+             "initial principal child list must have exactly one child");
+  nsContainerFrame::SetInitialChildList(kPrincipalList, aChildList);
+}
+
+void
+nsColumnSetFrame::AppendFrames(ChildListID     aListID,
+                               nsFrameList&    aFrameList)
+{
+  MOZ_CRASH("unsupported operation");
+}
+
+void
+nsColumnSetFrame::InsertFrames(ChildListID     aListID,
+                               nsIFrame*       aPrevFrame,
+                               nsFrameList&    aFrameList)
+{
+  MOZ_CRASH("unsupported operation");
+}
+
+void
+nsColumnSetFrame::RemoveFrame(ChildListID     aListID,
+                              nsIFrame*       aOldFrame)
+{
+  MOZ_CRASH("unsupported operation");
+}
+#endif