[Chromoting] Enable jscompile for webapp unittests.

remoting/webapp/js_proto/dom_proto.js

 // Copyright (c) 2012 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.
 
 // This file contains various hacks needed to inform JSCompiler of various
 // WebKit- and Chrome-specific properties and methods. It is used only with
 // JSCompiler to verify the type-correctness of our code.
 
 /** @type {Array<string>} */
 ClipboardData.prototype.types;
@@ skipping 27 matching lines @@
 
 /** @type {boolean} */
 Element.prototype.hidden;
 
 /** @type {string} */
 Element.prototype.innerText;
 
 /** @type {string} */
 Element.prototype.localName;
 
+/** @type {number} */
+Element.prototype.offsetRight;
+
+/** @type {number} */
+Element.prototype.offsetBottom;
+
 /** @type {string} */
 Element.prototype.textContent;
 
 /** @type {DOMTokenList} */
 Element.prototype.classList;
 
 /** @type {boolean} */
 Element.prototype.checked;
 
 
@@ skipping 69 matching lines @@
 
 /**
  * @param {*} value
  * @return {boolean} whether value is an integer or not.
  */
 Number.isInteger = function(value) {};
 
 // Chrome implements XMLHttpRequest.responseURL starting from Chrome 37.
 /** @type {string} */
 XMLHttpRequest.prototype.responseURL = "";