Bug 1367601 - Fix unified build error in imgRequestProxy.cpp. r=tnikkel

This file does not have a |using namespace mozilla;| line, so it cannot use
image::Image without a mozilla:: qualification.

image/imgRequestProxy.cpp

@@ -617,7 +617,7 @@ imgRequestProxy* NewStaticProxy(imgRequestProxy* aThis)
 {
   nsCOMPtr<nsIPrincipal> currentPrincipal;
   aThis->GetImagePrincipal(getter_AddRefs(currentPrincipal));
-  RefPtr<image::Image> image = aThis->GetImage();
+  RefPtr<mozilla::image::Image> image = aThis->GetImage();
   return new imgRequestProxyStatic(image, currentPrincipal);
 }