[Variables] Enable get/setProperty and similar APIs from the CSSOM

third_party/WebKit/Source/core/css/CSSValue.cpp

 /*
  * Copyright (C) 2011 Andreas Kling (kling@webkit.org)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 243 matching lines @@
         return toCSSValueList(this)->customCSSText();
     case ImageSetClass:
         return toCSSImageSetValue(this)->customCSSText();
     case CSSSVGDocumentClass:
         return toCSSSVGDocumentValue(this)->customCSSText();
     case CSSContentDistributionClass:
         return toCSSContentDistributionValue(this)->customCSSText();
     case VariableReferenceClass:
         return toCSSVariableReferenceValue(this)->customCSSText();
     case CustomPropertyDeclarationClass:
-        // TODO(leviw): We don't allow custom properties in CSSOM yet
-        ASSERT_NOT_REACHED();
+        return toCSSCustomPropertyDeclaration(this)->customCSSText();
     }
     ASSERT_NOT_REACHED();
     return String();
 }
 
 void CSSValue::destroy()
 {
     switch (classType()) {
     case BasicShapeCircleClass:
         delete toCSSBasicShapeCircleValue(this);
@@ skipping 349 matching lines @@
         toCSSVariableReferenceValue(this)->traceAfterDispatch(visitor);
         return;
     case CustomPropertyDeclarationClass:
         toCSSCustomPropertyDeclaration(this)->traceAfterDispatch(visitor);
         return;
     }
     ASSERT_NOT_REACHED();
 }
 
 }