[CSS Grid Layout] Use CSS_FR for flexible lengths instead of CSS_DIMENSION

Source/core/css/CSSComputedStyleDeclaration.cpp

 /*
  * Copyright (C) 2004 Zack Rusin <zack@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2011 Sencha, Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
@@ skipping 983 matching lines @@
             break;
         }
         list->append(filterValue.release());
     }
 
     return list.release();
 }
 
 static PassRefPtr<CSSValue> valueForGridTrackBreadth(const GridLength& trackBreadth, const RenderStyle* style, RenderView* renderView)
 {
-    if (!trackBreadth.isLength()) {
-        String flex = String::number(trackBreadth.flex()) + "fr";
-        return cssValuePool().createValue(flex, CSSPrimitiveValue::CSS_DIMENSION);
-    }
+    if (!trackBreadth.isLength())
+        return cssValuePool().createValue(trackBreadth.flex(), CSSPrimitiveValue::CSS_FR);
 
     const Length& trackBreadthLength = trackBreadth.length();
     if (trackBreadthLength.isAuto())
         return cssValuePool().createIdentifierValue(CSSValueAuto);
     if (trackBreadthLength.isViewportPercentage())
         return zoomAdjustedPixelValue(valueForLength(trackBreadthLength, 0, renderView), style);
     return zoomAdjustedPixelValueForLength(trackBreadthLength, style);
 }
 
 static PassRefPtr<CSSValue> valueForGridTrackSize(const GridTrackSize& trackSize, const RenderStyle* style, RenderView* renderView)
@@ skipping 2184 matching lines @@
     static const CSSPropertyID propertiesAfterSlashSeperator[3] = { CSSPropertyBackgroundSize, CSSPropertyBackgroundOrigin,
                                                                     CSSPropertyBackgroundClip };
 
     RefPtr<CSSValueList> list = CSSValueList::createSlashSeparated();
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesBeforeSlashSeperator, WTF_ARRAY_LENGTH(propertiesBeforeSlashSeperator))));
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesAfterSlashSeperator, WTF_ARRAY_LENGTH(propertiesAfterSlashSeperator))));
     return list.release();
 }
 
 } // namespace WebCore