DevTools: Remove unused variables. Disallow unused variables with eslint

third_party/WebKit/Source/devtools/front_end/sources/SourceMapNamesResolver.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.
 Sources.SourceMapNamesResolver = {};
 
 Sources.SourceMapNamesResolver._cachedMapSymbol = Symbol('cache');
 Sources.SourceMapNamesResolver._cachedIdentifiersSymbol = Symbol('cachedIdentifiers');
 
 /**
  * @unrestricted
@@ skipping 48 matching lines @@
    * @param {!Common.Text} text
    * @param {number} scopeStart
    * @param {string} prefix
    * @param {?MessageEvent} event
    * @return {!Array<!Sources.SourceMapNamesResolver.Identifier>}
    */
   function onIdentifiers(text, scopeStart, prefix, event) {
     var identifiers = event ? /** @type {!Array<!{name: string, offset: number}>} */ (event.data) : [];
     var result = [];
     var cursor = new Common.TextCursor(text.lineEndings());
-    var promises = [];
     for (var i = 0; i < identifiers.length; ++i) {
       var id = identifiers[i];
       if (id.offset < prefix.length)
         continue;
       var start = scopeStart + id.offset - prefix.length;
       cursor.resetTo(start);
       result.push(new Sources.SourceMapNamesResolver.Identifier(id.name, cursor.lineNumber(), cursor.columnNumber()));
     }
     return result;
   }
@@ skipping 461 matching lines @@
   }
 
   /**
    * @override
    * @return {boolean}
    */
   isNode() {
     return this._object.isNode();
   }
 };