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

Source/devtools/front_end/elements/MetricsSidebarPane.js

 /*
  * Copyright (C) 2007 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 36 matching lines @@
         // (if a CSS property is added, a StyleSheetChanged event is dispatched).
         if (this._isEditingMetrics) {
             finishedCallback();
             return;
         }
 
         // FIXME: avoid updates of a collapsed pane.
         var node = this.node();
         var cssModel = this.cssModel();
         if (!node || node.nodeType() !== Node.ELEMENT_NODE || !cssModel) {
-            this.bodyElement.removeChildren();
+            this.element.removeChildren();
             finishedCallback();
             return;
         }
 
         /**
          * @param {?WebInspector.CSSStyleDeclaration} style
          * @this {WebInspector.MetricsSidebarPane}
          */
         function callback(style)
         {
@@ skipping 228 matching lines @@
                 boxElement.appendChild(createBoxPartElement.call(this, style, name, "right", suffix));
                 boxElement.appendChild(createElement("br"));
                 boxElement.appendChild(createBoxPartElement.call(this, style, name, "bottom", suffix));
             }
 
             previousBox = boxElement;
         }
 
         metricsElement.appendChild(previousBox);
         metricsElement.addEventListener("mouseover", this._highlightDOMNode.bind(this, false, "all"), false);
-        this.bodyElement.removeChildren();
-        this.bodyElement.appendChild(metricsElement);
+        this.element.removeChildren();
+        this.element.appendChild(metricsElement);
     },
 
     startEditing: function(targetElement, box, styleProperty, computedStyle)
     {
         if (WebInspector.isBeingEdited(targetElement))
             return;
 
         var context = { box: box, styleProperty: styleProperty, computedStyle: computedStyle };
         var boundKeyDown = this._handleKeyDown.bind(this, context, styleProperty);
         context.keyDownHandler = boundKeyDown;
@@ skipping 138 matching lines @@
     },
 
     editingCommitted: function(element, userInput, previousContent, context)
     {
         this.editingEnded(element, context);
         this._applyUserInput(element, userInput, previousContent, context, true);
     },
 
     __proto__: WebInspector.ElementsSidebarPane.prototype
 }