Clean up forward declarations in Source/core/css

Source/core/css/CSSPropertySourceData.h

 /*
  * Copyright (c) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 21 matching lines @@
 #define CSSPropertySourceData_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class StyleRuleBase;
-
 struct SourceRange {
     ALLOW_ONLY_INLINE_ALLOCATION();
 public:
     SourceRange();
     SourceRange(unsigned start, unsigned end);
     unsigned length() const;
 
     void trace(Visitor*) { }
 
     unsigned start;
@@ skipping 86 matching lines @@
     // Only for CSSMediaRules.
     RuleSourceDataList childRules;
 };
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_AND_INIT_WITH_MEM_FUNCTIONS(blink::SourceRange);
 WTF_ALLOW_MOVE_AND_INIT_WITH_MEM_FUNCTIONS(blink::CSSPropertySourceData);
 
 #endif // CSSPropertySourceData_h