Add blink-side binding code and tests for ServiceWorker -> Document postMessage (3/3)

LayoutTests/http/tests/serviceworker/resources/postmessage-to-client-worker.js

Index: LayoutTests/http/tests/serviceworker/resources/postmessage-to-client-worker.js
diff --git a/LayoutTests/http/tests/serviceworker/resources/postmessage-to-client-worker.js b/LayoutTests/http/tests/serviceworker/resources/postmessage-to-client-worker.js
new file mode 100644
index 0000000000000000000000000000000000000000..2cc5e5dbc73611f2d649f717810b623ef0aadd2b
--- /dev/null
+++ b/LayoutTests/http/tests/serviceworker/resources/postmessage-to-client-worker.js
@@ -0,0 +1,10 @@
+var values = [];
+
+self.onmessage = function(e) {
+    self.clients.getServiced().then(function(clients) {
+        clients.forEach(function(client) {
+            client.postMessage('Sending message via clients');
+            client.postMessage('quit');
+        });
+    });
+};