Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/core/css/CSSFontSelectorClient.h

 /*
  * Copyright (C) 2014 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 CSSFontSelectorClient_h
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class CSSFontSelector;
 class Visitor;
 
-class CORE_EXPORT CSSFontSelectorClient : public WillBeGarbageCollectedMixin {
+class CORE_EXPORT CSSFontSelectorClient : public GarbageCollectedMixin {
 public:
     virtual ~CSSFontSelectorClient() { }
 
     virtual void fontsNeedUpdate(CSSFontSelector*) = 0;
 
     DEFINE_INLINE_VIRTUAL_TRACE() { }
 };
 
 } // namespace blink
 
 #endif // CSSFontSelectorClient_h