[CSS Grid Layout] Fix grid shorthands CSSOM serialization

Source/core/css/StylePropertySerializer.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Research In Motion Limited. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 399 matching lines @@
         return get4Values(borderStyleShorthand());
     case CSSPropertyWebkitColumnRule:
         return getShorthandValue(webkitColumnRuleShorthand());
     case CSSPropertyWebkitColumns:
         return getShorthandValue(webkitColumnsShorthand());
     case CSSPropertyFlex:
         return getShorthandValue(flexShorthand());
     case CSSPropertyFlexFlow:
         return getShorthandValue(flexFlowShorthand());
     case CSSPropertyGridColumn:
-        return getShorthandValue(gridColumnShorthand());
+        return getShorthandValue(gridColumnShorthand(), " / ");
     case CSSPropertyGridRow:
-        return getShorthandValue(gridRowShorthand());
+        return getShorthandValue(gridRowShorthand(), " / ");
     case CSSPropertyGridArea:
-        return getShorthandValue(gridAreaShorthand());
+        return getShorthandValue(gridAreaShorthand(), " / ");
     case CSSPropertyFont:
         return fontValue();
     case CSSPropertyMargin:
         return get4Values(marginShorthand());
     case CSSPropertyMotion:
         return getShorthandValue(motionShorthand());
     case CSSPropertyWebkitMarginCollapse:
         return getShorthandValue(webkitMarginCollapseShorthand());
     case CSSPropertyOverflow:
         return getCommonValue(overflowShorthand());
@@ skipping 309 matching lines @@
     }
 
     if (isInitialOrInherit(commonValue))
         return commonValue;
 
     if (result.isEmpty())
         return String();
     return result.toString();
 }
 
-String StylePropertySerializer::getShorthandValue(const StylePropertyShorthand& shorthand) const
+String StylePropertySerializer::getShorthandValue(const StylePropertyShorthand& shorthand, String separator) const
 {
     String commonValue;
     StringBuilder result;
     for (unsigned i = 0; i < shorthand.length(); ++i) {
         if (!m_propertySet.isPropertyImplicit(shorthand.properties()[i])) {
             const CSSValue* value = m_propertySet.getPropertyCSSValue(shorthand.properties()[i]);
             if (!value)
                 return String();
             String valueText = value->cssText();
             if (!i)
                 commonValue = valueText;
             else if (!commonValue.isNull() && commonValue != valueText)
                 commonValue = String();
             if (value->isInitialValue())
                 continue;
             if (!result.isEmpty())
-                result.append(' ');
+                result.append(separator);
             result.append(valueText);
         } else
             commonValue = String();
     }
     if (isInitialOrInherit(commonValue))
         return commonValue;
     if (result.isEmpty())
         return String();
     return result.toString();
 }
@@ skipping 211 matching lines @@
             isInitialValue = false;
         if (!value->isInheritedValue())
             isInheritedValue = false;
         if (isImportant != m_propertySet.propertyIsImportant(shorthand.properties()[i]))
             return false;
     }
     return isInitialValue || isInheritedValue;
 }
 
 }