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

Source/devtools/front_end/layers/LayersPanel.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 26 matching lines @@
  * @extends {WebInspector.PanelWithSidebarTree}
  */
 WebInspector.LayersPanel = function()
 {
     WebInspector.PanelWithSidebarTree.call(this, "layers", 225);
     this.registerRequiredCSS("layersPanel.css");
 
     this.sidebarElement().classList.add("outline-disclosure");
     this.sidebarTree.element.classList.remove("sidebar-tree");
 
-    this._target = /** @type {!WebInspector.Target} */ (WebInspector.targetManager.activeTarget());
+    this._target = /** @type {!WebInspector.Target} */ (WebInspector.targetManager.mainTarget());
     this._model = new WebInspector.LayerTreeModel(this._target);
     this._model.addEventListener(WebInspector.LayerTreeModel.Events.LayerTreeChanged, this._onLayerTreeUpdated, this);
     this._model.addEventListener(WebInspector.LayerTreeModel.Events.LayerPainted, this._onLayerPainted, this);
     this._currentlySelectedLayer = null;
     this._currentlyHoveredLayer = null;
 
     this._layerTreeOutline = new WebInspector.LayerTreeOutline(this.sidebarTree);
     this._layerTreeOutline.addEventListener(WebInspector.LayerTreeOutline.Events.LayerSelected, this._onObjectSelected, this);
     this._layerTreeOutline.addEventListener(WebInspector.LayerTreeOutline.Events.LayerHovered, this._onObjectHovered, this);
 
@@ skipping 156 matching lines @@
      */
     reveal: function(snapshotData)
     {
         if (!(snapshotData instanceof WebInspector.DeferredLayerTree))
             return;
         var panel = /** @type {?WebInspector.LayersPanel} */ (WebInspector.inspectorView.showPanel("layers"));
         if (panel)
             panel._showLayerTree(/** @type {!WebInspector.DeferredLayerTree} */ (snapshotData));
     }
 }