Bug 1335801 - Wait for the right events. r=Felipe,krizsa

MozReview-Commit-ID: JL0AdE8XB2n

--HG--
extra : rebase_source : ad6392315710cea34e583a9cabfc878ee225f186

browser/base/content/test/referrer/head.js

@@ -140,19 +140,7 @@ function delayedStartupFinished(aWindow) {
  * @resolves With the tab once it's loaded.
  */
 function someTabLoaded(aWindow) {
-  return new Promise(function(resolve) {
-    aWindow.gBrowser.addEventListener("load", function onLoad(aEvent) {
-      if (aWindow.location.href === "about:blank") {
-        return;
-      }
-      let tab = aWindow.gBrowser._getTabForContentWindow(
-          aEvent.target.defaultView.top);
-      if (tab) {
-        aWindow.gBrowser.removeEventListener("load", onLoad, true);
-        resolve(tab);
-      }
-    }, true);
-  });
+  return BrowserTestUtils.waitForNewTab(aWindow.gBrowser);
 }
 
 /**