ServiceWorker: Add support for .skipWaiting and controllerchange event(1/3)

LayoutTests/http/tests/serviceworker/resources/skip-waiting-installed-worker.js

+self.state = 'starting';
+
+self.addEventListener('install', function() {
+    self.state = 'installing';
+  });
+
+self.addEventListener('activate', function() {
+    self.state = 'activating';
+  });
+
+self.addEventListener('message', function(event) {
+    var port = event.data.port;
+    if (self.state !== 'installing') {
+      port.postMessage('FAIL: Worker should waiting in installed state');

[falken, 2014/12/01 02:28:48]

nit: "be waiting"?

[xiang, 2014/12/01 07:13:44]

Done.

+      return;
+    }
+    self.skipWaiting()
+      .then(function(result) {
+          if (result !== undefined) {
+            port.postMessage('FAIL: Promise should be resolved with undefined');
+            return;
+          }
+          if (self.state !== 'activating') {
+            port.postMessage(
+                'FAIL: Promise should be resolved after worker activated');
+            return;
+          }
+          port.postMessage('PASS');
+        })
+      .catch(function(e) {
+          port.postMessage('FAIL: unexpected exception: ' + e);
+        });
+  });