[part 1] Make classes and structures in modules/ fast-allocated.

Source/modules/encryptedmedia/MediaKeysClient.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MediaKeysClient_h
 #define MediaKeysClient_h
 
+#include "wtf/FastAllocBase.h"
+
 namespace blink {
 
 class ExecutionContext;
 class WebEncryptedMediaClient;
 
 class MediaKeysClient {
+    WTF_MAKE_FAST_ALLOCATED(MediaKeysClient);
 public:
     virtual WebEncryptedMediaClient* encryptedMediaClient(ExecutionContext*) = 0;
 
 protected:
     virtual ~MediaKeysClient() { }
 };
 
 } // namespace blink
 
 #endif // MediaKeysClient_h