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 101947da171ad711430ed55206bb94312d9ccae2..245b632674a26379e8a791691bc3f247c7656938 100644
--- a/Source/core/rendering/RenderFlexibleBox.cpp
+++ b/Source/core/rendering/RenderFlexibleBox.cpp
@@ -609,7 +609,7 @@ 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);
@@ -991,6 +991,14 @@ 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());
@@ -1351,10 +1359,11 @@ void RenderFlexibleBox::applyStretchAlignmentToChild(RenderBox& child, LayoutUni
             LayoutUnit stretchedLogicalHeight = heightBeforeStretching + availableAlignmentSpaceForChildBeforeStretching(lineCrossAxisExtent, child);
             ASSERT(!child.needsLayout());
             LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, heightBeforeStretching - child.borderAndPaddingLogicalHeight());
+            LayoutUnit desiredLogicalContentHeight = desiredLogicalHeight - child.borderAndPaddingLogicalHeight();
 
             // FIXME: Can avoid laying out here in some cases. See https://webkit.org/b/87905.
-            if (desiredLogicalHeight != child.logicalHeight()) {
-                child.setOverrideLogicalContentHeight(desiredLogicalHeight - child.borderAndPaddingLogicalHeight());
+            if (desiredLogicalHeight != child.logicalHeight() || (!child.hasOverrideHeight() && toRenderBlock(child).hasPercentHeightDescendants())) {
+                child.setOverrideLogicalContentHeight(desiredLogicalContentHeight);
                 child.setLogicalHeight(0);
                 child.forceChildLayout();
             }