DevTools: migrate sidebar pane's titleElement to use Toolbar.

Source/devtools/front_end/sources/ThreadsSidebarPane.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.
 
 /**
  * @constructor
  * @extends {WebInspector.SidebarPane}
  * @implements {WebInspector.TargetManager.Observer}
  */
 WebInspector.ThreadsSidebarPane = function()
 {
     WebInspector.SidebarPane.call(this, WebInspector.UIString("Threads"));
     this.setVisible(false);
 
     /** @type {!Map.<!WebInspector.DebuggerModel, !WebInspector.UIList.Item>} */
     this._debuggerModelToListItems = new Map();
     /** @type {!Map.<!WebInspector.UIList.Item, !WebInspector.Target>} */
     this._listItemsToTargets = new Map();
     /** @type {?WebInspector.UIList.Item} */
     this._selectedListItem = null;
     this.threadList = new WebInspector.UIList();
-    this.threadList.show(this.bodyElement);
+    this.threadList.show(this.element);
     WebInspector.targetManager.addModelListener(WebInspector.DebuggerModel, WebInspector.DebuggerModel.Events.DebuggerPaused, this._onDebuggerStateChanged, this);
     WebInspector.targetManager.addModelListener(WebInspector.DebuggerModel, WebInspector.DebuggerModel.Events.DebuggerResumed, this._onDebuggerStateChanged, this);
     WebInspector.context.addFlavorChangeListener(WebInspector.Target, this._targetChanged, this);
     WebInspector.targetManager.observeTargets(this);
 }
 
 WebInspector.ThreadsSidebarPane.prototype = {
     /**
      * @override
      * @param {!WebInspector.Target} target
@@ skipping 92 matching lines @@
      */
     _onListItemClick: function(listItem)
     {
         WebInspector.context.setFlavor(WebInspector.Target, this._listItemsToTargets.get(listItem));
         listItem.element.scrollIntoViewIfNeeded();
     },
 
 
     __proto__: WebInspector.SidebarPane.prototype
 }