[WebUI TaskManager] Fix JS check nits in chrome/browser/resources/task_manager.

chrome/browser/resources/task_manager/measure_time.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.
 
 /**
  * @fileoverview Utility methods for measuring loading times.
  *
  * To be included as a first script in main.html
  */
 
+/**
+ * measureTime class
+ * @constructor
+ */
 var measureTime = {
   isEnabled: localStorage.measureTimeEnabled,
 
   startInterval: function(name) {
     if (this.isEnabled)
       console.time(name);
   },
 
   recordInterval: function(name) {
     if (this.isEnabled)
       console.timeEnd(name);
   },
 };
 
 measureTime.startInterval('Load.Total');
 measureTime.startInterval('Load.Script');