Issue #29 - Interpret empty or whitespace root margin string as zero length for the IntersectionObserver

Credit to FranklinDM

2 files changed, 19 insertions, 3 deletions

diff --git a/dom/base/DOMIntersectionObserver.cpp b/dom/base/DOMIntersectionObserver.cpp
index bc8f030d0..fb6315cc4 100644
--- a/dom/base/DOMIntersectionObserver.cpp
+++ b/dom/base/DOMIntersectionObserver.cpp
@@ -126,7 +126,9 @@ DOMIntersectionObserver::SetRootMargin(const nsAString& aString)
 
   for (uint32_t i = 0; i < ArrayLength(nsCSSRect::sides); ++i) {
     nsCSSValue value = mRootMargin.*nsCSSRect::sides[i];
-    if (!(value.IsPixelLengthUnit() || value.IsPercentLengthUnit())) {
+    if (!(value.IsPixelLengthUnit() ||
+          value.IsPercentLengthUnit() ||
+          value.IsFloatUnit(value.GetUnit()))) {
       return false;
     }
   }
@@ -327,6 +329,8 @@ DOMIntersectionObserver::Update(nsIDocument* aDocument, DOMHighResTimeStamp time
     nsStyleCoord coord;
     if (value.IsPixelLengthUnit()) {
       coord.SetCoordValue(value.GetPixelLength());
+    } else if (value.IsFloatUnit(value.GetUnit())) {
+      coord.SetCoordValue(value.GetFloatValue());
     } else if (value.IsPercentLengthUnit()) {
       coord.SetPercentValue(value.GetPercentValue());
     } else {
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index f3df2df20..72427792f 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -2300,8 +2300,20 @@ CSSParserImpl::ParseMarginString(const nsSubstring& aBuffer,
 
   nsAutoSuppressErrors suppressErrors(this, aSuppressErrors);
 
-  // Parse a margin, and check that there's nothing else after it.
-  bool marginParsed = ParseGroupedBoxProperty(VARIANT_LP, aValue, 0) && !GetToken(true);
+  bool marginParsed = false;
+
+  // Treat margin as zero length if there are no tokens, i.e., the specified
+  // margin string is empty or consists only of whitespace characters.
+  if (!GetToken(true)) {
+    nsCSSRect& zeroRootMargin = aValue.SetRectValue();
+    zeroRootMargin.SetAllSidesTo(nsCSSValue(0.0f, eCSSUnit_Pixel));
+    marginParsed = true;
+  } else {
+    UngetToken();
+    // Parse a margin, and check that there's nothing else after it.
+    marginParsed = ParseGroupedBoxProperty(VARIANT_LPN, aValue, 0) &&
+                   !GetToken(true);
+  }
 
   if (aSuppressErrors) {
     CLEAR_ERROR();