Fix the issue of skip-waiting-installed.https.html

According to the current spec, skipWaiting() promise should be resolved
earlier even in the case that the service worker state is "installed",
and then continues the activate in parallel. The test case violate that.

The background is in w3c/ServiceWorker#1015.

BUG=725616

Change-Id: Ic09b4d404ea41138c8bda8d3ced07094a7ebc6ab
Reviewed-on: https://chromium-review.googlesource.com/571612
Cr-Commit-Position: refs/heads/master@{#487754}
WPT-Export-Revision: 8d477e09e22742fee30abee882e5349ef539b5e3

service-workers/service-worker/skip-waiting-installed.https.html

@@ -20,15 +20,14 @@
           assert_equals(
             message, 'PASS',
             'skipWaiting promise should be resolved with undefined');
-
-          assert_equals(registration.active.scriptURL, normalizeURL(url2),
-                        'skipWaiting should make worker become active');
         });
     var saw_controllerchanged = new Promise(function(resolve) {
         oncontrollerchanged = function() {
             assert_equals(
                 frame_sw.controller.scriptURL, normalizeURL(url2),
                 'Controller scriptURL should change to the second one');
+            assert_equals(registration.active.scriptURL, normalizeURL(url2),
+                          'worker should be active by controllerchange');
             resolve();
         };
       });