DevTools: [CSS] promisify CSSStyleModel fetching methods

Source/devtools/front_end/elements/SharedSidebarModel.js

 // Copyright (c) 2015 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.
 
 /**
  * @extends {WebInspector.Object}
  * @constructor
  */
 WebInspector.SharedSidebarModel = function()
 {
@@ skipping 89 matching lines @@
      * @return {!Promise.<?WebInspector.SharedSidebarModel.ComputedStyle>}
      */
     fetchComputedStyle: function()
     {
         var elementNode = this._elementNode();
         var cssModel = this.cssModel();
         if (!elementNode || !cssModel)
             return Promise.resolve(/** @type {?WebInspector.SharedSidebarModel.ComputedStyle} */(null));
 
         if (!this._computedStylePromise)
-            this._computedStylePromise = new Promise(getComputedStyle.bind(null, elementNode)).then(verifyOutdated.bind(this, elementNode));
+            this._computedStylePromise = cssModel.computedStylePromise(elementNode.id).then(verifyOutdated.bind(this, elementNode));
 
         return this._computedStylePromise;
 
         /**
          * @param {!WebInspector.DOMNode} elementNode
-         * @param {function(?WebInspector.CSSStyleDeclaration)} resolve
-         */
-        function getComputedStyle(elementNode, resolve)
-        {
-            cssModel.getComputedStyleAsync(elementNode.id, resolve);
-        }
-
-        /**
-         * @param {!WebInspector.DOMNode} elementNode
          * @param {?WebInspector.CSSStyleDeclaration} style
          * @return {?WebInspector.SharedSidebarModel.ComputedStyle}
          * @this {WebInspector.SharedSidebarModel}
          */
         function verifyOutdated(elementNode, style)
         {
             return elementNode === this._elementNode() && style ? new WebInspector.SharedSidebarModel.ComputedStyle(elementNode, style) : /** @type {?WebInspector.SharedSidebarModel.ComputedStyle} */(null);
         }
     },
 
     _onComputedStyleChanged: function()
     {
         delete this._computedStylePromise;
         this.dispatchEventToListeners(WebInspector.SharedSidebarModel.Events.ComputedStyleChanged);
     },
 
     __proto__: WebInspector.Object.prototype
 }
 
 /**
  * @constructor
  * @param {!WebInspector.DOMNode} node
  * @param {!WebInspector.CSSStyleDeclaration} computedStyle
  */
 WebInspector.SharedSidebarModel.ComputedStyle = function(node, computedStyle)
 {
     this.node = node;
     this.computedStyle = computedStyle;
 }