Fix fullscreen elements in pinch viewport mode.

Source/core/frame/PinchViewport.h

Index: Source/core/frame/PinchViewport.h
diff --git a/Source/core/frame/PinchViewport.h b/Source/core/frame/PinchViewport.h
index 6ab9b65a16a32d419cfd42fddd04225dd148e964..d9d26ccb6283b9a0d052c5ab8b8d4f0c37718d7c 100644
--- a/Source/core/frame/PinchViewport.h
+++ b/Source/core/frame/PinchViewport.h
@@ -79,6 +79,10 @@ public:
     {
         return m_innerViewportContainerLayer.get();
     }
+    GraphicsLayer* scrollLayer()
+    {
+        return m_innerViewportScrollLayer.get();
+    }
 
     // Sets the location of the inner viewport relative to the outer viewport. The
     // coordinates are in partial CSS pixels.