Bug 1182247 - Only RegisterPluginForGeometryUpdates in nsPluginFrame::EndSwapDocShells if mInstanceOwner is non-null. r=tnikkel

Having a non-null mInstanceOwner corresponds to when registration
normally happens (from nsPluginInstanceOwner::SetFrame), and it's
disconnecting the instance owner that leads to unregistration.

MozReview-Commit-ID: 3X15t9zoXIj

layout/generic/nsPluginFrame.cpp

@@ -1866,7 +1866,9 @@ nsPluginFrame::EndSwapDocShells(nsISupports* aSupports, void*)
     }
   }
 
-  objectFrame->RegisterPluginForGeometryUpdates();
+  if (objectFrame->mInstanceOwner) {
+    objectFrame->RegisterPluginForGeometryUpdates();
+  }
 }
 
 nsIFrame*