Support 'extend-to-zoom' viewport descriptor value

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 2726 matching lines @@
             LayoutUnit availableLogicalWidth = 0;
             return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
         }
         case ViewportPercentageWidth:
         case ViewportPercentageHeight:
         case ViewportPercentageMin:
         case ViewportPercentageMax:
             return adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, 0, view()));
         case FitContent:
         case FillAvailable:
-        case Percent: 
+        case Percent:
         case Calculated: {
             // FIXME: containingBlockLogicalWidthForContent() is wrong if the replaced element's block-flow is perpendicular to the
             // 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));
         }
         // fall through
         case Intrinsic:
         case MinIntrinsic:
         case Auto:
         case Relative:
+        case ExtendToZoom:
         case Undefined:
             return intrinsicLogicalWidth();
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 LayoutUnit RenderBox::computeReplacedLogicalHeight() const
 {
@@ skipping 1852 matching lines @@
     }
 
     if (didSplitParentAnonymousBoxes)
         markBoxForRelayoutAfterSplit(this);
 
     ASSERT(beforeChild->parent() == this);
     return beforeChild;
 }
 
 } // namespace WebCore