Print Preview: Make getChildElement return required HTMLElement

chrome/browser/resources/print_preview/settings/copies_settings.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.
 
 cr.define('print_preview', function() {
   'use strict';
 
   /**
    * Component that renders the copies settings UI.
    * @param {!print_preview.ticket_items.Copies} copiesTicketItem Used to read
@@ skipping 67 matching lines @@
       this.inputField_.disabled = !isEnabled;
       this.getChildElement('input.collate').disabled = !isEnabled;
       this.isEnabled_ = isEnabled;
       if (isEnabled) {
         this.updateState_();
       }
     },
 
     /** @override */
     enterDocument: function() {
-      this.inputField_ = assert(this.getChildElement('input.user-value'));
+      this.inputField_ = this.getChildElement('input.user-value');
       print_preview.SettingsSection.prototype.enterDocument.call(this);
       this.tracker.add(
           this.inputField_,
           'keydown',
           this.onTextfieldKeyDown_.bind(this));
       this.tracker.add(
           this.inputField_,
           'input',
           this.onTextfieldInput_.bind(this));
       this.tracker.add(
           this.inputField_,
           'blur',
           this.onTextfieldBlur_.bind(this));
       this.tracker.add(
-          assert(this.getChildElement('input.collate')),
+          this.getChildElement('input.collate'),
           'click',
           this.onCollateCheckboxClick_.bind(this));
       this.tracker.add(
           this.copiesTicketItem_,
           print_preview.ticket_items.TicketItem.EventType.CHANGE,
           this.updateState_.bind(this));
       this.tracker.add(
           this.collateTicketItem_,
           print_preview.ticket_items.TicketItem.EventType.CHANGE,
           this.updateState_.bind(this));
@@ skipping 96 matching lines @@
       this.collateTicketItem_.updateValue(
           this.getChildElement('input.collate').checked);
     }
   };
 
   // Export
   return {
     CopiesSettings: CopiesSettings
   };
 });