Remove forward declarations from Source/core/dom/custom

Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.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:
  *
  * 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
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef CustomElementAsyncImportMicrotaskQueue_h
 #define CustomElementAsyncImportMicrotaskQueue_h
 
 #include "core/dom/custom/CustomElementMicrotaskQueueBase.h"
 
 namespace blink {
 
-class CustomElementMicrotaskImportStep;
-
 class CustomElementAsyncImportMicrotaskQueue : public CustomElementMicrotaskQueueBase {
 public:
     static PassRefPtrWillBeRawPtr<CustomElementAsyncImportMicrotaskQueue> create() { return adoptRefWillBeNoop(new CustomElementAsyncImportMicrotaskQueue()); }
 
     void enqueue(PassOwnPtrWillBeRawPtr<CustomElementMicrotaskStep>);
 
 private:
     CustomElementAsyncImportMicrotaskQueue() { }
     virtual void doDispatch() OVERRIDE;
 };
 
-}
+} // namespace blink
+
 #endif // CustomElementAsyncImportMicrotaskQueue_h