Bug 1379055 - Remove unused member of WebRenderPaintedLayerBlob r=jrmuizel

gfx/layers/wr/WebRenderPaintedLayerBlob.h

@@ -53,8 +53,6 @@ public:
   void RenderLayer(wr::DisplayListBuilder& aBuilder,
                    const StackingContextHelper& aSc) override;
 private:
-  RefPtr<ImageContainer> mImageContainer;
-  RefPtr<ImageClient> mImageClient;
   Maybe<WrImageKey> mImageKey;
   LayerIntRect mImageBounds;
 };