Don't use intrinsic width if our container's width is zero.

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 2766 matching lines @@
             // containing block's block-flow.
             // https://bugs.webkit.org/show_bug.cgi?id=46496
             const LayoutUnit cw = isOutOfFlowPositioned() ? containingBlockLogicalWidthForPositioned(toRenderBoxModelObject(container())) : containingBlockLogicalWidthForContent();
             Length containerLogicalWidth = containingBlock()->style()->logicalWidth();
             // FIXME: Handle cases when containing block width is calculated or viewport percent.
             // https://bugs.webkit.org/show_bug.cgi?id=91071
             if (logicalWidth.isIntrinsic())
                 return computeIntrinsicLogicalWidthUsing(logicalWidth, cw, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
             if (cw > 0 || (!cw && (containerLogicalWidth.isFixed() || containerLogicalWidth.isPercent())))
                 return adjustContentBoxLogicalWidthForBoxSizing(minimumValueForLength(logicalWidth, cw));
+            return 0;
         }
-        // fall through
         case Intrinsic:
         case MinIntrinsic:
         case Auto:
         case Undefined:
             return intrinsicLogicalWidth();
         case ExtendToZoom:
         case DeviceWidth:
         case DeviceHeight:
             break;
     }
@@ skipping 1863 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore