Bug 1120652 - Remove MainThreadFetchResolver::OnResponseEnd() and provide an empty definition in the parent class FetchDriverObserver. r=nsm

dom/fetch/Fetch.cpp

@@ -136,9 +136,6 @@ public:
   void
   OnResponseAvailable(InternalResponse* aResponse) MOZ_OVERRIDE;
 
-  void
-  OnResponseEnd() MOZ_OVERRIDE;
-
 private:
   ~MainThreadFetchResolver();
 };
@@ -265,14 +262,6 @@ MainThreadFetchResolver::OnResponseAvailable(InternalResponse* aResponse)
   mPromise->MaybeResolve(mResponse);
 }
 
-void
-MainThreadFetchResolver::OnResponseEnd()
-{
-  NS_ASSERT_OWNINGTHREAD(MainThreadFetchResolver);
-  AssertIsOnMainThread();
-  MOZ_ASSERT(mResponse);
-}
-
 MainThreadFetchResolver::~MainThreadFetchResolver()
 {
   NS_ASSERT_OWNINGTHREAD(MainThreadFetchResolver);

dom/fetch/FetchDriver.h

@@ -31,7 +31,8 @@ class FetchDriverObserver
 public:
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FetchDriverObserver);
   virtual void OnResponseAvailable(InternalResponse* aResponse) = 0;
-  virtual void OnResponseEnd() = 0;
+  virtual void OnResponseEnd()
+  { };
 
 protected:
   virtual ~FetchDriverObserver()