DevTools: use timing information for "disk cached" resources.

Source/devtools/front_end/audits/AuditRules.js

 /*
  * Copyright (C) 2010 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 76 matching lines @@
      * @param {!WebInspector.Progress} progress
      */
     doRun: function(target, requests, result, callback, progress)
     {
         var totalSavings = 0;
         var compressedSize = 0;
         var candidateSize = 0;
         var summary = result.addChild("", true);
         for (var i = 0, length = requests.length; i < length; ++i) {
             var request = requests[i];
-            if (request.cached || request.statusCode === 304)
+            if (request.cached() || request.statusCode === 304)
                 continue; // Do not test cached resources.
             if (this._shouldCompress(request)) {
                 var size = request.resourceSize;
                 candidateSize += size;
                 if (this._isCompressed(request)) {
                     compressedSize += size;
                     continue;
                 }
                 var savings = 2 * size / 3;
                 totalSavings += savings;
@@ skipping 1484 matching lines @@
         result.violationCount = badUrls.length;
     },
 
     _collectorCallback: function(matchingResourceData, request, cookie)
     {
         matchingResourceData[request.url] = (matchingResourceData[request.url] || 0) + cookie.size();
     },
 
     __proto__: WebInspector.AuditRules.CookieRuleBase.prototype
 }