[VR Shell] Fix hidden elements being hit-testable.

chrome/browser/resources/vr_shell/vr_shell_ui_api.js

 // Copyright 2016 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.
 
 var api = {};
 
 /**
  * Enumeration of scene update commands.
  * @enum {number}
  * @const
@@ skipping 122 matching lines @@
  * Abstract fill base class.
  * @abstract
  */
 api.Fill = class {
   constructor(type) {
     this.properties = {};
     this.properties['fillType'] = type;
   }
 }
 
+api.NoFill = class extends api.Fill {
+  constructor() {
+    super(api.FillType.NONE);
+  }
+}
+
 api.Sprite = class extends api.Fill {
   constructor(pixelX, pixelY, pixelWidth, pixelHeight) {
     super(api.FillType.SPRITE);
     this.properties['copyRectX'] = pixelX;
     this.properties['copyRectY'] = pixelY;
     this.properties['copyRectWidth'] = pixelWidth;
     this.properties['copyRectHeight'] = pixelHeight;
   }
 }
 
@@ skipping 509 matching lines @@
     if ('updateTab' in dict) {
       this.onUpdateTab(dict['updateTab']);
     }
     if ('removeTab' in dict) {
       this.onRemoveTab(dict['removeTab']);
     }
 
     this.onCommandHandlerFinished()
   }
 };