DevTools: [CSS] promisify CSSStyleModel fetching methods

Source/devtools/front_end/elements/PlatformFontsWidget.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 53 matching lines @@
      * @protected
      */
     doUpdate: function(finishedCallback)
     {
         var cssModel = this._sharedModel.cssModel();
         var node = this._sharedModel.node();
         if (!node || !cssModel) {
             finishedCallback();
             return;
         }
-        cssModel.getPlatformFontsForNode(node.id, this._refreshUI.bind(this, node, finishedCallback));
+        cssModel.platformFontsPromise(node.id)
+            .then(this._refreshUI.bind(this, node))
+            .then(finishedCallback)
+            .catch(/** @type {function()} */(finishedCallback));
     },
 
     /**
      * @param {!WebInspector.DOMNode} node
-     * @param {!WebInspector.Throttler.FinishCallback} finishedCallback
      * @param {?Array.<!CSSAgent.PlatformFontUsage>} platformFonts
      */
-    _refreshUI: function(node, finishedCallback, platformFonts)
+    _refreshUI: function(node, platformFonts)
     {
-        if (this._sharedModel.node() !== node) {
-            finishedCallback();
+        if (this._sharedModel.node() !== node)
             return;
-        }
 
         this._fontStatsSection.removeChildren();
 
         var isEmptySection = !platformFonts || !platformFonts.length;
         this._sectionTitle.classList.toggle("hidden", isEmptySection);
-        if (isEmptySection) {
-            finishedCallback();
+        if (isEmptySection)
             return;
-        }
+
         platformFonts.sort(function (a, b) {
             return b.glyphCount - a.glyphCount;
         });
         for (var i = 0; i < platformFonts.length; ++i) {
             var fontStatElement = this._fontStatsSection.createChild("div", "font-stats-item");
 
             var fontNameElement = fontStatElement.createChild("span", "font-name");
             fontNameElement.textContent = platformFonts[i].familyName;
 
             var fontDelimeterElement = fontStatElement.createChild("span", "delimeter");
             fontDelimeterElement.textContent = "\u2014";
 
             var fontUsageElement = fontStatElement.createChild("span", "font-usage");
             var usage = platformFonts[i].glyphCount;
             fontUsageElement.textContent = usage === 1 ? WebInspector.UIString("%d glyph", usage) : WebInspector.UIString("%d glyphs", usage);
         }
-        finishedCallback();
     },
 
     __proto__: WebInspector.ThrottledWidget.prototype
 }