Oilpan: make DOMWindowProperty a GC mixin.

Source/modules/webmidi/NavigatorWebMIDI.h

Index: Source/modules/webmidi/NavigatorWebMIDI.h
diff --git a/Source/modules/webmidi/NavigatorWebMIDI.h b/Source/modules/webmidi/NavigatorWebMIDI.h
index 0cdba7ed5d6a0cbe64ab134be520b01515333deb..8fdbbd743eb7464f4a2b7b2fe440ce618c834fe4 100644
--- a/Source/modules/webmidi/NavigatorWebMIDI.h
+++ b/Source/modules/webmidi/NavigatorWebMIDI.h
@@ -41,16 +41,16 @@ namespace blink {
 
 class Navigator;
 
-class NavigatorWebMIDI FINAL : public NoBaseWillBeGarbageCollectedFinalized<NavigatorWebMIDI>, public WillBeHeapSupplement<Navigator>, public DOMWindowProperty {
+class NavigatorWebMIDI FINAL : public NoBaseWillBeGarbageCollected<NavigatorWebMIDI>, public WillBeHeapSupplement<Navigator>, public DOMWindowProperty {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(NavigatorWebMIDI);
+    DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(NavigatorWebMIDI);
 public:
-    virtual ~NavigatorWebMIDI();
     static NavigatorWebMIDI& from(Navigator&);
 
     static ScriptPromise requestMIDIAccess(ScriptState*, Navigator&, const Dictionary&);
     ScriptPromise requestMIDIAccess(ScriptState*, const Dictionary&);
 
-    virtual void trace(Visitor* visitor) OVERRIDE { WillBeHeapSupplement<Navigator>::trace(visitor); }
+    virtual void trace(Visitor*) OVERRIDE;
 
 private:
     NavigatorWebMIDI(LocalFrame*);