Clean up forward declarations in Source/core

Source/core/animation/ActiveAnimations.h

 /*
  * Copyright (C) 2013 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 23 matching lines @@
 #include "core/animation/AnimationStack.h"
 #include "core/animation/css/CSSAnimations.h"
 #include "wtf/HashCountedSet.h"
 #include "wtf/HashMap.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class CSSAnimations;
-class RenderObject;
-class Element;
 
 using AnimationPlayerCountedSet = WillBeHeapHashCountedSet<RawPtrWillBeWeakMember<AnimationPlayer>>;
 
 class ActiveAnimations : public NoBaseWillBeGarbageCollectedFinalized<ActiveAnimations> {
     WTF_MAKE_NONCOPYABLE(ActiveAnimations);
 public:
     ActiveAnimations();
     ~ActiveAnimations();
 
     // Animations that are currently active for this element, their effects will be applied
@@ skipping 42 matching lines @@
     Vector<Animation*> m_animations;
 #endif
 
     // CSSAnimations checks if a style change is due to animation.
     friend class CSSAnimations;
 };
 
 } // namespace blink
 
 #endif