Bug 1288606 - Fix intermittent orange by making sure a weakly held nsISHistoryListener doesn't get GC'd before the browser_bug670318.js completes. r=jaws

MozReview-Commit-ID: AWvpK6OpmmI

--HG--
extra : rebase_source : 40863e55308f18a6f4172fe74fad323c0ad9cc38

docshell/test/browser/browser_bug670318.js

@@ -31,6 +31,7 @@ add_task(function* test() {
             }, true);
 
             history.removeSHistoryListener(listener);
+            delete content._testListener;
             content.setTimeout(() => { content.location.reload(); }, 0);
           }
 
@@ -55,7 +56,14 @@ add_task(function* test() {
       };
 
       history.addSHistoryListener(listener);
+      // Since listener implements nsISupportsWeakReference, we are
+      // responsible for keeping it alive so that the GC doesn't clear
+      // it before the test completes. We do this by anchoring the listener
+      // to the content global window, and clearing it just before the test
+      // completes.
+      content._testListener = listener;
       content.location = URL;
+
       yield testDone.promise;
     });
   });