Add some small tests for jQuery postMessage definition file.

jquery.postMessage/jquery.postMessage-test.ts

@@ -0,0 +1,28 @@
+/// <reference path="jquery.postMessage.d.ts" />
+/// <reference path="../jquery/jquery.d.ts" />
+
+function test_postMessage() {
+    // post plain message
+    $.postMessage('test message', 'http://dummy.url/', parent);
+
+    // post object message
+    $.postMessage({
+        'a': '1',
+        'b': '2'
+    }, 'http://dummy.url/', parent);
+};
+
+function test_receiveMessage() {
+    // receive plain source origin
+    $.receiveMessage((e) => {
+        // e is an instance of MessageEvent
+        console.log(e.data);
+        console.log(e.source);
+        console.log(e.origin);
+    }, 'http://dummy.url');
+
+    // receive source origin callback
+    $.receiveMessage((e) => {}, (sourceOrigin) => {
+        return sourceOrigin === 'http://dummy.url';
+    }, 100);
+};