Add ServiceWorker InstallPhaseEvent.waitUntil() layout test.

LayoutTests/http/tests/serviceworker/resources/install-phase-event-waituntil.js

+var pendingPorts = [];
+var portResolves = [];
+
+onmessage = function(e) {
+    var message = e.data;
+    if ('port' in message) {
+        var resolve = self.portResolves.shift();
+        if (resolve)
+            resolve(message.port);
+        else
+            self.pendingPorts.push(message.port);
+    }
+};
+
+function fulfillPromise() {
+    return new Promise(function(resolve) {
+        // Make sure oninstall/onactivate callback finishes first.

[jsbell, 2014/07/01 16:16:48]

Is it really necessary for this to run in a subsequent tick of the even loop, or
is just running in a subsequent microtask sufficient?

If it's just after the callback finishes, then a microtask would be sufficient,
e.g.:

return Promise.resolve().then(function() {
  var port = ...
}).then(function(port) { 
  ... 
});

If it does need to be in a subsequent turn of the event loop, can you document
that?

[xiang, 2014/07/02 05:10:42]

Yes, microtask is sufficient here, thanks!

+        setTimeout(function() {
+            var port = self.pendingPorts.shift();
+            if (port)
+                resolve(port);
+            else
+                self.portResolves.push(resolve);
+        }, 0);
+    }).then(function(port) {
+        port.postMessage('SYNC');
+        return new Promise(function(resolve) {
+            port.onmessage = function(e) {
+                if (e.data == 'ACK')
+                    resolve();
+            };
+        });
+    });
+}
+
+function rejectPromise() {
+    return new Promise(function(resolve, reject) {
+        setTimeout(reject, 0);

[jsbell, 2014/07/01 16:16:48]

Add comment similar to the above, i.e. why `return Promise.reject()` is not
sufficient.

[xiang, 2014/07/02 05:10:42]

will add.

+    });
+}
+
+function stripScopeName(scope) {
+    return scope.split('/').slice(-1)[0];
+}
+
+oninstall = function(e) {
+    switch (stripScopeName(self.scope)) {
+        case 'install-fulfilled':
+            e.waitUntil(fulfillPromise());
+            break;
+        case 'install-rejected':
+            e.waitUntil(rejectPromise());
+            break;
+    }
+};
+
+onactivate = function(e) {
+    switch (stripScopeName(self.scope)) {
+        case 'activate-fulfilled':
+            e.waitUntil(fulfillPromise());
+            break;
+        case 'activate-rejected':
+            e.waitUntil(rejectPromise());
+            break;
+        case 'activate-multiple-fulfilled':
+            e.waitUntil(fulfillPromise());
+            e.waitUntil(fulfillPromise());
+            break;
+        case 'activate-reject-precedence':
+            e.waitUntil(fulfillPromise());
+            e.waitUntil(new Promise(function(resolve, reject) {

[jsbell, 2014/07/01 16:16:48]

Why not rejectPromise() here?

[xiang, 2014/07/02 05:10:42]

Sure, I will change it.

+                setTimeout(reject, 0);
+            }));
+            break;
+    }
+};