DevTools: introduce "Track CSS Usage" experiment

third_party/WebKit/Source/devtools/front_end/devtools_compatibility.js

 // Copyright 2014 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.
 /* eslint-disable indent */
 (function(window) {
 
   // DevToolsAPI ----------------------------------------------------------------
 
   /**
    * @unrestricted
@@ skipping 943 matching lines @@
       'textEditorAutocompletion',
       'textEditorAutoDetectIndent',
       'textEditorBracketMatching',
       'textEditorIndent',
       'timelineCaptureFilmStrip',
       'timelineCaptureLayersAndPictures',
       'timelineCaptureMemory',
       'timelineCaptureNetwork',
       'timeline-details',
       'timelineEnableJSSampling',
+      'timelineMarkUnusedCSS',

[caseq, 2016/11/04 21:10:02]

WAT? Why has this changed?

       'timelineOverviewMode',
       'timelinePanelDetailsSplitViewState',
       'timelinePanelRecorsSplitViewState',
       'timelinePanelTimelineStackSplitViewState',
       'timelinePerspective',
       'timeline-split',
       'timelineTreeGroupBy',
       'timeline-view',
       'timelineViewMode',
       'uiTheme',
@@ skipping 257 matching lines @@
      * @return {boolean}
      */
     DOMTokenList.prototype.toggle = function(token, force) {
       if (arguments.length === 1)
         force = !this.contains(token);
       return this.__originalDOMTokenListToggle(token, !!force);
     };
   }
 
 })(window);