Bug 883416 (Part 1) - Revert bug 851416. r=dholbert

--HG--
extra : rebase_source : 47dae82941038ff7f79f15aee50194276f617f9b

image/src/VectorImage.cpp

@@ -84,16 +84,11 @@ protected:
       }
 
       mVectorImage->InvalidateObserver();
-
-      // We may have been removed from the observer list by our caller. Rather
-      // than add ourselves back here, we wait until Draw gets called, ensuring
-      // that we coalesce invalidations between Draw calls.
-    } else {
-      // Here we may also have been removed from the observer list, but since
-      // we're not sending an invalidation, Draw won't get called. We need to
-      // add ourselves back immediately.
-      ResumeListening();
     }
+
+    // We may have been removed from the observer list by our caller. Rather
+    // than add ourselves back here, we wait until Draw gets called, ensuring
+    // that we coalesce invalidations between Draw calls.
   }
 
   // Private data