Don't stretch margin: auto items in a vertical flexbox

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 2163 matching lines @@
         logicalWidthResult = min(logicalWidthResult, shrinkLogicalWidthToAvoidFloats(marginStart, marginEnd, cb, region, offsetFromLogicalTopOfFirstPage));        
 
     if (widthType == MainOrPreferredSize && sizesLogicalWidthToFitContent(widthType))
         return max(minPreferredLogicalWidth(), min(maxPreferredLogicalWidth(), logicalWidthResult));
     return logicalWidthResult;
 }
 
 static bool flexItemHasStretchAlignment(const RenderObject* flexitem)
 {
     RenderObject* parent = flexitem->parent();
+    // auto margins mean we don't stretch. Note that this function will only be used for
+    // widths, so we don't have to check marginBefore/marginAfter.

[ojan, 2013/05/24 22:39:09]

Instead of adding (or maybe in addition to) the extra "Note" section, how about
adding an ASSERT(parent()->style()->isColumnFlexDirection()); and renaming this
function to columnFlexItemHasStretchAlignment?

+    if (flexitem->style()->marginStart().isAuto() || flexitem->style()->marginEnd().isAuto())
+        return false;
     return flexitem->style()->alignSelf() == AlignStretch || (flexitem->style()->alignSelf() == AlignAuto && parent->style()->alignItems() == AlignStretch);
 }
 
 static bool isStretchingColumnFlexItem(const RenderObject* flexitem)
 {
     RenderObject* parent = flexitem->parent();
     if (parent->isDeprecatedFlexibleBox() && parent->style()->boxOrient() == VERTICAL && parent->style()->boxAlign() == BSTRETCH)
         return true;
 
     // We don't stretch multiline flexboxes because they need to apply line spacing (align-content) first.
@@ skipping 2397 matching lines @@
 
 void RenderBox::reportStaticMembersMemoryUsage(MemoryInstrumentation* memoryInstrumentation)
 {
     memoryInstrumentation->addRootObject(gOverrideHeightMap, WebCoreMemoryTypes::RenderingStructures);
     memoryInstrumentation->addRootObject(gOverrideWidthMap, WebCoreMemoryTypes::RenderingStructures);
     memoryInstrumentation->addRootObject(gOverrideContainingBlockLogicalHeightMap, WebCoreMemoryTypes::RenderingStructures);
     memoryInstrumentation->addRootObject(gOverrideContainingBlockLogicalWidthMap, WebCoreMemoryTypes::RenderingStructures);
 }
 
 } // namespace WebCore