Bug 1198663. Tolerate null Image in Android NPAPI plugins. r=snorp

--HG--
extra : commitid : FdJDH9TFrxW
extra : rebase_source : c68370c63e82749ac8a376a0449820e789f1a124

dom/plugins/base/nsPluginInstanceOwner.cpp

@@ -238,9 +238,10 @@ nsPluginInstanceOwner::GetImageContainer()
   if (!img) {
     AttachToContainerAsSurfaceTexture(container, mInstance, r, &img);
   }
-  MOZ_ASSERT(img);
 
-  container->SetCurrentImageInTransaction(img);
+  if (img) {
+    container->SetCurrentImageInTransaction(img);
+  }
 #else
   mInstance->GetImageContainer(getter_AddRefs(container));
 #endif