[Chromoting] Enable jscompile for webapp unittests.

remoting/webapp/unittests/xmpp_stream_parser_unittest.js

 // Copyright 2014 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.
 
 (function() {
 
 'use strict';
 
+/** @type {Function} */
 var onStanzaStr = null;
-var onError = null;
+
+/** @type {function(string):void} */
+var onError = function(msg) {};
+
+/** @type {remoting.XmppStreamParser} */
 var parser = null;
 
 module('XmppStreamParser', {
   setup: function() {
     onStanzaStr = sinon.spy();
-    onError = sinon.spy();
+    onError = /** @type {function(string):void} */ (sinon.spy());
+    /** @param {Element} stanza */
     function onStanza(stanza) {
       onStanzaStr(new XMLSerializer().serializeToString(stanza));
     }
     parser = new remoting.XmppStreamParser();
     parser.setCallbacks(onStanza, onError);
   }
 });
 
 
 test('should parse XMPP stream', function() {
@@ skipping 53 matching lines @@
 test('should fail on incomplete UTF-8 sequences', function() {
   var buffer = base.encodeUtf8('<stream><iq>ф')
   // Crop last byte.
   buffer = buffer.slice(0, buffer.byteLength - 1);
   parser.appendData(buffer);
   parser.appendData(base.encodeUtf8('</iq>'));
   sinon.assert.calledWith(onError);
 });
 
 })();