1 files changed, 17 insertions, 22 deletions

diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index 1c5ade583..47026b73c 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -327,6 +327,7 @@ WrapBackgroundColorInOwnLayer(nsDisplayListBuilder* aBuilder,
 
 void
 nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
+                                     const nsRect&           aDirtyRect,
                                      const nsDisplayListSet& aLists)
 {
   if (!IsVisibleForPainting(aBuilder))
@@ -342,7 +343,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   bool pointerEventsNone =
     StyleUserInterface()->mPointerEvents == NS_STYLE_POINTER_EVENTS_NONE;
   if (!aBuilder->IsForEventDelivery() || !pointerEventsNone) {
-    nsDisplayListCollection decorations(aBuilder);
+    nsDisplayListCollection decorations;
     DisplayBorderBackgroundOutline(aBuilder, decorations);
     if (rfp) {
       // Wrap background colors of <iframe>s with remote subdocuments in their
@@ -367,7 +368,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   }
 
   if (rfp) {
-    rfp->BuildDisplayList(aBuilder, this, aLists);
+    rfp->BuildDisplayList(aBuilder, this, aDirtyRect, aLists);
     return;
   }
 
@@ -386,28 +387,23 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   int32_t parentAPD = PresContext()->AppUnitsPerDevPixel();
   int32_t subdocAPD = presContext->AppUnitsPerDevPixel();
 
-  nsRect visible;
   nsRect dirty;
   bool haveDisplayPort = false;
   bool ignoreViewportScrolling = false;
   nsIFrame* savedIgnoreScrollFrame = nullptr;
   if (subdocRootFrame) {
     // get the dirty rect relative to the root frame of the subdoc
-    visible = aBuilder->GetVisibleRect() + GetOffsetToCrossDoc(subdocRootFrame);
-    dirty = aBuilder->GetDirtyRect() + GetOffsetToCrossDoc(subdocRootFrame);
+    dirty = aDirtyRect + GetOffsetToCrossDoc(subdocRootFrame);
     // and convert into the appunits of the subdoc
-    visible = visible.ScaleToOtherAppUnitsRoundOut(parentAPD, subdocAPD);
     dirty = dirty.ScaleToOtherAppUnitsRoundOut(parentAPD, subdocAPD);
 
     if (nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame()) {
       nsIScrollableFrame* rootScrollableFrame = presShell->GetRootScrollFrameAsScrollable();
       MOZ_ASSERT(rootScrollableFrame);
-      // Use a copy, so the rects don't get modified.
-      nsRect copyOfDirty = dirty;
-      nsRect copyOfVisible = visible;
+      // Use a copy, so the dirty rect doesn't get modified to the display port.
+      nsRect copy = dirty;
       haveDisplayPort = rootScrollableFrame->DecideScrollableLayer(aBuilder,
-                          &copyOfVisible, &copyOfDirty,
-                          /* aAllowCreateDisplayPort = */ true);
+                          &copy, /* aAllowCreateDisplayPort = */ true);
       if (!gfxPrefs::LayoutUseContainersForRootFrames()) {
         haveDisplayPort = false;
       }
@@ -421,8 +417,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
     aBuilder->EnterPresShell(subdocRootFrame, pointerEventsNone);
   } else {
-    visible = aBuilder->GetVisibleRect();
-    dirty = aBuilder->GetDirtyRect();
+    dirty = aDirtyRect;
   }
 
   DisplayListClipState::AutoSaveRestore clipState(aBuilder);
@@ -461,13 +456,6 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       nestedClipState.EnterStackingContextContents(true);
     }
 
-    // Invoke AutoBuildingDisplayList to ensure that the correct dirty rect
-    // is used to compute the visible rect if AddCanvasBackgroundColorItem
-    // creates a display item.
-    nsIFrame* frame = subdocRootFrame ? subdocRootFrame : this;
-    nsDisplayListBuilder::AutoBuildingDisplayList
-      building(aBuilder, frame, visible, dirty, true);
-
     if (subdocRootFrame) {
       nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame();
       nsDisplayListBuilder::AutoCurrentScrollParentIdSetter idSetter(
@@ -478,7 +466,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
       aBuilder->SetAncestorHasApzAwareEventHandler(false);
       subdocRootFrame->
-        BuildDisplayListForStackingContext(aBuilder, &childItems);
+        BuildDisplayListForStackingContext(aBuilder, dirty, &childItems);
     }
 
     if (!aBuilder->IsForEventDelivery()) {
@@ -497,8 +485,15 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       // painted on the page itself.
       if (nsLayoutUtils::NeedsPrintPreviewBackground(presContext)) {
         presShell->AddPrintPreviewBackgroundItem(
-          *aBuilder, childItems, frame, bounds);
+          *aBuilder, childItems, subdocRootFrame ? subdocRootFrame : this,
+          bounds);
       } else {
+        // Invoke AutoBuildingDisplayList to ensure that the correct dirty rect
+        // is used to compute the visible rect if AddCanvasBackgroundColorItem
+        // creates a display item.
+        nsIFrame* frame = subdocRootFrame ? subdocRootFrame : this;
+        nsDisplayListBuilder::AutoBuildingDisplayList
+          building(aBuilder, frame, dirty, true);
         // Add the canvas background color to the bottom of the list. This
         // happens after we've built the list so that AddCanvasBackgroundColorItem
         // can monkey with the contents if necessary.