Bug 1462272: Remove an unneeded and ugly reinterpret_cast. r=dholbert

MozReview-Commit-ID: Evip43nwNii

layout/generic/nsImageFrame.cpp

@@ -214,7 +214,7 @@ nsImageFrame::DestroyFrom(nsIFrame* aDestructRoot, PostDestroyData& aPostDestroy
       imageLoader->RemoveNativeObserver(mListener);
     }
 
-    reinterpret_cast<nsImageListener*>(mListener.get())->SetFrame(nullptr);
+    mListener->SetFrame(nullptr);
   }
 
   mListener = nullptr;

layout/generic/nsImageFrame.h

@@ -331,7 +331,7 @@ private:
 
   RefPtr<nsImageMap> mImageMap;
 
-  nsCOMPtr<imgINotificationObserver> mListener;
+  RefPtr<nsImageListener> mListener;
 
   nsCOMPtr<imgIContainer> mImage;
   nsCOMPtr<imgIContainer> mPrevImage;