ServiceWorker: "minimal" end-to-end sample as a W3C test

LayoutTests/http/tests/serviceworker/resources/end-to-end-worker.js

+oninstall = function(e) {
+    e.waitUntil(new Promise(function(r) { setTimeout(r, 5); }));

[jsbell, 2014/04/16 17:43:38]

I'm not happy with using setTimeout in this test. I'd prefer to go back to
having a ping/pong protocol. Why was it removed?

[kinuko, 2014/04/17 11:32:54]

I wanted to make this test dead simple / 'minimal', feel free to revert it

+};
+
+onactivate = function(e) {
+    e.waitUntil(new Promise(function(r) { setTimeout(r, 5); }));
+};
+
+onmessage = function(e) {
+    var message = e.data;
+    if (typeof message === 'object' && 'port' in message) {

[jsbell, 2014/04/16 17:43:38]

FWIW, `typeof null === 'object'`; the `Object(x) === x` I'd used handles that
case, but is more subtle. I suppose `typeof x === 'object' && x !== null` would
be the clearest.

[kinuko, 2014/04/17 11:32:54]

Yup, sgtm, please feel free to fix it.

+        var response = 'Ack for: ' + message.from;
+        try {
+            message.port.postMessage(response);
+        } catch (_) {}
+    }
+};