[css-grid] Implement grid gutters

third_party/WebKit/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 410 matching lines @@
     case CSSPropertyFlex:
         return getShorthandValue(flexShorthand());
     case CSSPropertyFlexFlow:
         return getShorthandValue(flexFlowShorthand());
     case CSSPropertyGridColumn:
         return getShorthandValue(gridColumnShorthand(), " / ");
     case CSSPropertyGridRow:
         return getShorthandValue(gridRowShorthand(), " / ");
     case CSSPropertyGridArea:
         return getShorthandValue(gridAreaShorthand(), " / ");
+    case CSSPropertyGridGap:
+        return getShorthandValue(gridGapShorthand());
     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 528 matching lines @@
             isInitialValue = false;
         if (!value->isInheritedValue())
             isInheritedValue = false;
         if (isImportant != m_propertySet.propertyIsImportant(shorthand.properties()[i]))
             return false;
     }
     return isInitialValue || isInheritedValue;
 }
 
 }