DevTools: get rid of WebInspector.cssModel, use target models instead

Source/devtools/front_end/timeline/TimelinePanel.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel 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.
@@ skipping 58 matching lines @@
     this.registerRequiredCSS("layersPanel.css");
     this.registerRequiredCSS("filter.css");
     this.element.addEventListener("contextmenu", this._contextMenu.bind(this), false);
 
     this._detailsLinkifier = new WebInspector.Linkifier();
     this._windowStartTime = 0;
     this._windowEndTime = Infinity;
 
     // Create model.
     if (WebInspector.experimentsSettings.timelineOnTraceEvents.isEnabled()) {
-        this._tracingModel = new WebInspector.TracingModel(WebInspector.targetManager.activeTarget());
+        this._tracingModel = new WebInspector.TracingModel(WebInspector.targetManager.mainTarget());
         this._tracingModel.addEventListener(WebInspector.TracingModel.Events.BufferUsage, this._onTracingBufferUsage, this);
 
         this._uiUtils = new WebInspector.TracingTimelineUIUtils();
         this._tracingTimelineModel = new WebInspector.TracingTimelineModel(this._tracingModel, this._uiUtils.hiddenRecordsFilter());
         this._model = this._tracingTimelineModel;
     } else {
         this._uiUtils = new WebInspector.TimelineUIUtilsImpl();
         this._model = new WebInspector.TimelineModelImpl(WebInspector.timelineManager);
     }
 
@@ skipping 1380 matching lines @@
      * @param {!WebInspector.TimelineModel.Record} record
      * @return {boolean}
      */
     accept: function(record)
     {
         return !this._regex || this._uiUtils.testContentMatching(record, this._regex);
     },
 
     __proto__: WebInspector.TimelineModel.Filter.prototype
 }