Blink doesn't honor percent heights on children of "align-self:stretch" flex items in a fixed-height

Source/core/rendering/RenderFlexibleBox.cpp

Index: Source/core/rendering/RenderFlexibleBox.cpp
diff --git a/Source/core/rendering/RenderFlexibleBox.cpp b/Source/core/rendering/RenderFlexibleBox.cpp
index 3a948cb7201ad76ee5b9b8a7be06f21007b20e34..ca0c8e4eb2ae074010d3d66784bda7595f471a33 100644
--- a/Source/core/rendering/RenderFlexibleBox.cpp
+++ b/Source/core/rendering/RenderFlexibleBox.cpp
@@ -612,7 +612,7 @@ bool RenderFlexibleBox::childPreferredMainAxisContentExtentRequiresLayout(Render
 
 LayoutUnit RenderFlexibleBox::preferredMainAxisContentExtentForChild(RenderBox& child, bool hasInfiniteLineLength, bool relayoutChildren)
 {
-    child.clearOverrideSize();
+    clearLogicalOverrideSize(child);
 
     if (child.style()->hasAspectRatio() || child.isImage() || child.isVideo() || child.isCanvas())
         UseCounter::count(document(), UseCounter::AspectRatioFlexItem);
@@ -994,6 +994,14 @@ void RenderFlexibleBox::setLogicalOverrideSize(RenderBox& child, LayoutUnit chil
         child.setOverrideLogicalContentWidth(childPreferredSize - child.borderAndPaddingLogicalWidth());
 }
 
+void RenderFlexibleBox::clearLogicalOverrideSize(RenderBox& child)
+{
+    if (hasOrthogonalFlow(child))
+        child.clearOverrideLogicalContentHeight();
+    else
+        child.clearOverrideLogicalContentWidth();
+}
+
 void RenderFlexibleBox::prepareChildForPositionedLayout(RenderBox& child, LayoutUnit mainAxisOffset, LayoutUnit crossAxisOffset, PositionedLayoutMode layoutMode)
 {
     ASSERT(child.isOutOfFlowPositioned());
@@ -1356,7 +1364,7 @@ void RenderFlexibleBox::applyStretchAlignmentToChild(RenderBox& child, LayoutUni
             LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, heightBeforeStretching - child.borderAndPaddingLogicalHeight());
 
             // FIXME: Can avoid laying out here in some cases. See https://webkit.org/b/87905.
-            if (desiredLogicalHeight != child.logicalHeight()) {
+            if (!child.hasOverrideHeight() || ((desiredLogicalHeight - child.borderAndPaddingLogicalHeight()) != child.overrideLogicalContentHeight())) {

[cbiesinger, 2014/09/25 00:50:31]

I think you have to *also* keep desiredLogicalHeight != child.logicalHeight() as
a condition here because there could be a change to the height of the child, in
which case we'd not relayout.

Also, please make desiredLogicalHeight - child.borderAndPaddingLogicalHeight() a
local variable so that the if is easier to read.

[harpreet.sk, 2014/09/25 12:58:57]

Done.

                 child.setOverrideLogicalContentHeight(desiredLogicalHeight - child.borderAndPaddingLogicalHeight());
                 child.setLogicalHeight(0);
                 child.forceChildLayout();