DevTools: Remove unused variables. Disallow unused variables with eslint

third_party/WebKit/Source/devtools/front_end/timeline_model/TimelineFrameModel.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 305 matching lines @@
       this.handleRequestMainThreadFrame();
     else if (event.name === eventNames.NeedsBeginFrameChanged)
       this.handleNeedFrameChanged(timestamp, event.args['data'] && event.args['data']['needsBeginFrame']);
   }
 
   /**
    * @param {!SDK.TracingModel.Event} event
    */
   _addMainThreadTraceEvent(event) {
     var eventNames = TimelineModel.TimelineModel.RecordType;
-    var timestamp = event.startTime;
-    var selfTime = event.selfTime || 0;
 
     if (SDK.TracingModel.isTopLevelEvent(event)) {
       this._currentTaskTimeByCategory = {};
       this._lastTaskBeginTime = event.startTime;
     }
     if (!this._framePendingCommit && TimelineModel.TimelineFrameModel._mainFrameMarkers.indexOf(event.name) >= 0) {
       this._framePendingCommit =
           new TimelineModel.PendingFrame(this._lastTaskBeginTime || event.startTime, this._currentTaskTimeByCategory);
     }
     if (!this._framePendingCommit) {
@@ skipping 207 matching lines @@
   constructor(triggerTime, timeByCategory) {
     /** @type {!Object.<string, number>} */
     this.timeByCategory = timeByCategory;
     /** @type {!Array.<!TimelineModel.LayerPaintEvent>} */
     this.paints = [];
     /** @type {number|undefined} */
     this.mainFrameId = undefined;
     this.triggerTime = triggerTime;
   }
 };