Avoid to include IDL-generated headers from EventTarget.h and Node.h

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannel.h

 // Copyright 2016 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 BroadcastChannel_h
 #define BroadcastChannel_h
 
 #include "bindings/core/v8/ActiveScriptWrappable.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/events/EventTarget.h"
 #include "mojo/public/cpp/bindings/associated_binding.h"
 #include "platform/weborigin/SecurityOrigin.h"
 #include "third_party/WebKit/public/platform/modules/broadcastchannel/broadcast_channel.mojom-blink.h"
 
 namespace blink {
 
+class ScriptValue;
+
 class BroadcastChannel final : public EventTargetWithInlineData,
                                public ActiveScriptWrappable<BroadcastChannel>,
                                public ContextLifecycleObserver,
                                public mojom::blink::BroadcastChannelClient {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(BroadcastChannel);
   USING_PRE_FINALIZER(BroadcastChannel, dispose);
   WTF_MAKE_NONCOPYABLE(BroadcastChannel);
 
  public:
@@ skipping 35 matching lines @@
   RefPtr<SecurityOrigin> m_origin;
   String m_name;
 
   mojo::AssociatedBinding<mojom::blink::BroadcastChannelClient> m_binding;
   mojom::blink::BroadcastChannelClientAssociatedPtr m_remoteClient;
 };
 
 }  // namespace blink
 
 #endif  // BroadcastChannel_h