Change mojo JS bindings to expose a handle object, which is Closed when garbage

mojo/apps/js/bindings/connection_unittests.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Mock out the support module to avoid depending on the message loop.
 define("mojo/bindings/js/support", function() {
   var waitingCallbacks = [];
 
   function WaitCookie(id) {
     this.id = id;
@@ skipping 35 matching lines @@
   return exports;
 });
 
 define([
     "gin/test/expect",
     "mojo/bindings/js/support",
     "mojo/bindings/js/core",
     "mojo/public/bindings/js/connection",
     "mojo/public/interfaces/bindings/tests/sample_interfaces.mojom",
     "mojo/public/interfaces/bindings/tests/sample_service.mojom",
+    "gc",
 ], function(expect,
             mockSupport,
             core,
             connection,
             sample_interfaces,
-            sample_service) {
+            sample_service,
+            gc) {
   testClientServer();
   testWriteToClosedPipe();
   testRequestResponse();
   this.result = "PASS";
+  gc.collectGarbage();  // should not crash
 
   function testClientServer() {
     var receivedFrobinate = false;
     var receivedDidFrobinate = false;
 
     // ServiceImpl -------------------------------------------------------------
 
     function ServiceImpl(peer) {
       this.peer = peer;
     }
@@ skipping 152 matching lines @@
 
     connection1.remote.echoStrings("hello", "world", function(a, b) {
       echoedString = a + " " + b;
     });
 
     mockSupport.pumpOnce(core.RESULT_OK);
 
     expect(echoedString).toBe("hello world");
   }
 });