ServiceWorker: Add LayoutTest for WindowClient.navigate().

LayoutTests/http/tests/serviceworker/resources/windowclient-navigate.js

+self.onmessage = function(e) {
+  var url = e.data;
+  var host;
+  var client;
+
+  self.clients.matchAll({ includeUncontrolled : true }).then(function(cs) {
+    cs.forEach(function(c) {
+      if (c.url.search('#message') != -1)
+        host = c;
+      else if (c.url.search('#client') != -1)
+        client= c;
+    });
+    client.navigate(url).then(function(c) {
+      if (!c)
+        host.postMessage(c);
+      else
+        host.postMessage(c.url);
+    }).catch(function(e) {
+      host.postMessage(e.name);
+    });

[nhiroki, 2015/09/28 08:59:21]

promise-chain indent (see my other comment)

client.navigate(url).then(function(c)) {
      ...
    })
  .catch(function(e) {
      ...
    });

[zino, 2015/10/07 02:30:41]

Done.

+  });
+};