Disable offsetWidth optimization in perparation for disabling it on M30.

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 392 matching lines @@
     return snapSizeToPixel(offsetWidth(), x() + clientLeft());
 }
 
 int RenderBox::pixelSnappedOffsetHeight() const
 {
     return snapSizeToPixel(offsetHeight(), y() + clientTop());
 }
 
 bool RenderBox::canDetermineWidthWithoutLayout() const
 {
-    // THIS OPTIMIZATION IS INCORRECT AS WRITTEN.
+    // FIXME: This optimization is incorrect as written.
+    // We need to be able to opt-in to this behavior only when
+    // it's guarentted correct.

[abarth-chromium, 2013/10/07 21:17:47]

typo: guarentted

+    // Until then disabling this optimization to be safe.
+    return false;
+
     // FIXME: There are likely many subclasses of RenderBlockFlow which
     // cannot determine their layout just from style!
     // Perhaps we should create a "PlainRenderBlockFlow"
     // and move this optimization there?
     if (!isRenderBlockFlow()
         // Flexbox items can be expanded beyond their width.
         || isFlexItemIncludingDeprecated()
         // Table Layout controls cell size and can expand beyond width.
         || isTableCell())
         return false;
@@ skipping 4359 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore