Make ActiveScriptWrappable the GC mixin it is.

third_party/WebKit/Source/modules/compositorworker/CompositorWorker.h

 // Copyright 2015 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 CompositorWorker_h
 #define CompositorWorker_h
 
 #include "core/workers/InProcessWorkerBase.h"
 #include "modules/ModulesExport.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class ExceptionState;
 class ExecutionContext;
 class InProcessWorkerGlobalScopeProxy;
 
 class MODULES_EXPORT CompositorWorker final : public InProcessWorkerBase {
     DEFINE_WRAPPERTYPEINFO();
+    USING_GARBAGE_COLLECTED_MIXIN(CompositorWorker);
 public:
     static CompositorWorker* create(ExecutionContext*, const String& url, ExceptionState&);
     ~CompositorWorker() override;
 
     const AtomicString& interfaceName() const override;
     InProcessWorkerGlobalScopeProxy* createInProcessWorkerGlobalScopeProxy(ExecutionContext*) override;
 
 private:
     explicit CompositorWorker(ExecutionContext*);
 };
 
 } // namespace blink
 
 #endif // CompositorWorker_h