[MediaRouter UI] Compile MR WebUI js code with Closure.

chrome/browser/resources/media_router/elements/issue_banner/issue_banner.js

 // Copyright 2015 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 Polymer element is used to show information about issues related
 // to casting.
 Polymer({
   is: 'issue-banner',
 
   properties: {
@@ skipping 95 matching lines @@
     this.fireIssueActionClick_(this.issue.defaultActionType);
   },
 
   /**
    * Called when an optional issue action is clicked.
    *
    * @param {!Event} event The event object.
    * @private
    */
   onClickOptAction_: function(event) {
-    this.fireIssueActionClick_(this.issue.secondaryActionType);
+    this.fireIssueActionClick_(
+        /** @type {number} */(this.issue.secondaryActionType));
   },
 
   /**
    * Called when |issue| is updated. This updates the default and secondary
    * action button text.
    *
    * @private
    */
   updateActionButtonText_: function() {
     var defaultText = '';
     var secondaryText = '';
     if (this.issue) {
       defaultText = loadTimeData.getString(
           this.actionTypeToButtonTextResource_[
           this.issue.defaultActionType]);
 
       if (this.issue.secondaryActionType) {
         secondaryText = loadTimeData.getString(
             this.actionTypeToButtonTextResource_[
             this.issue.secondaryActionType]);
       }
     }
 
     this.defaultActionButtonText_ = defaultText;
     this.secondaryActionButtonText_ = secondaryText;
   },
 });