DevTools: Remove unused variables. Disallow unused variables with eslint

third_party/WebKit/Source/devtools/front_end/accessibility/AccessibilityNodeView.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.
 /**
  * @unrestricted
  */
 Accessibility.AXNodeSubPane = class extends Accessibility.AccessibilitySubPane {
   constructor() {
     super(Common.UIString('Computed Properties'));
 
@@ skipping 329 matching lines @@
     var nodeTreeElement =
         new Accessibility.AXRelatedNodeSourceTreeElement({deferredNode: deferredNode, idref: idref}, relatedNode);
     this.appendChild(nodeTreeElement);
   }
 
   /**
    * @param {!Protocol.Accessibility.AXValue} value
    */
   appendIDRefValueElement(value) {
     var relatedNodes = value.relatedNodes;
-    var numNodes = relatedNodes.length;
-    var valueElement;
 
     var idrefs = value.value.trim().split(/\s+/);
     if (idrefs.length === 1) {
       var idref = idrefs[0];
       var matchingNode = relatedNodes.find(node => node.idref === idref);
       if (matchingNode)
         this.appendRelatedNodeWithIdref(matchingNode, 0, idref);
       else
         this.listItemElement.appendChild(new Accessibility.AXRelatedNodeElement({idref: idref}).render());
 
@@ skipping 31 matching lines @@
       this.collapse();
   }
 
   /**
    * @param {!Protocol.Accessibility.AXValueSource} source
    */
   appendSourceNameElement(source) {
     var nameElement = createElement('span');
     var AXValueSourceType = Protocol.Accessibility.AXValueSourceType;
     var type = source.type;
-    var name;
     switch (type) {
       case AXValueSourceType.Attribute:
       case AXValueSourceType.Placeholder:
       case AXValueSourceType.RelatedElement:
         if (source.nativeSource) {
           var AXNativeSourceTypes = Accessibility.AccessibilityStrings.AXNativeSourceTypes;
           var nativeSource = source.nativeSource;
           nameElement.textContent = Common.UIString(AXNativeSourceTypes[nativeSource].name);
           nameElement.title = Common.UIString(AXNativeSourceTypes[nativeSource].description);
           nameElement.classList.add('ax-readable-name');
@@ skipping 237 matching lines @@
 
     this._reasonElement =
         Accessibility.AXNodeIgnoredReasonTreeElement.createReasonElement(this._property.name, this._axNode);
     this.listItemElement.appendChild(this._reasonElement);
 
     var value = this._property.value;
     if (value.type === Protocol.Accessibility.AXValueType.Idref)
       this.appendRelatedNodeListValueElement(value);
   }
 };