WebUI: Fix/suppress some existing violations of no-restricted-globals.

chrome/browser/resources/hotword_audio_verification/flow.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() {
 
   // Correspond to steps in the hotword opt-in flow.
   /** @const */ var START = 'start-container';
   /** @const */ var AUDIO_HISTORY = 'audio-history-container';
   /** @const */ var SPEECH_TRAINING = 'speech-training-container';
@@ skipping 532 matching lines @@
     this.advanceStep();
   };
 
   /**
    * Displays the current step. If the current step is not the first step,
    * also hides the previous step. Focuses the current step's first button.
    * @private
    */
   Flow.prototype.showStep_ = function() {
     var currentStepId = this.currentFlow_[this.currentStepIndex_];
-    var currentStep = document.getElementById(currentStepId);
+    var currentStep = $(currentStepId);
     currentStep.hidden = false;
 
     cr.ui.setInitialFocus(currentStep);
 
     var previousStep = null;
     if (this.currentStepIndex_ > 0)
       previousStep = this.currentFlow_[this.currentStepIndex_ - 1];
 
     if (previousStep)
-      document.getElementById(previousStep).hidden = true;
+      $(previousStep).hidden = true;
 
     chrome.app.window.current().show();
   };
 
   window.Flow = Flow;
 })();