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

Source/core/rendering/RenderBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 2655 matching lines @@
     // A positioned element that specified both top/bottom or that specifies height should be treated as though it has a height
     // explicitly specified that can be used for any percentage computations.
     bool isOutOfFlowPositionedWithSpecifiedHeight = cb->isOutOfFlowPositioned() && (!cbstyle->logicalHeight().isAuto() || (!cbstyle->logicalTop().isAuto() && !cbstyle->logicalBottom().isAuto()));
 
     bool includeBorderPadding = isTable();
 
     if (isHorizontalWritingMode() != cb->isHorizontalWritingMode())
         availableHeight = containingBlockChild->containingBlockLogicalWidthForContent();
     else if (hasOverrideContainingBlockLogicalHeight())
         availableHeight = overrideContainingBlockContentLogicalHeight();
+    else if (cb->isFlexItem() && cb->hasOverrideContainingBlockLogicalHeight())
+        availableHeight = cb->overrideContainingBlockContentLogicalHeight();
     else if (cb->isTableCell()) {
         if (!skippedAutoHeightContainingBlock) {
             // Table cells violate what the CSS spec says to do with heights. Basically we
             // don't care if the cell specified a height or not. We just always make ourselves
             // be a percentage of the cell's current content height.
             if (!cb->hasOverrideHeight()) {
                 // Normally we would let the cell size intrinsically, but scrolling overflow has to be
                 // treated differently, since WinIE lets scrolled overflow regions shrink as needed.
                 // While we can't get all cases right, we can at least detect when the cell has a specified
                 // height or when the table has a specified height. In these cases we want to initially have
@@ skipping 1957 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore