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

Source/devtools/front_end/ui/Widget.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 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:
  * 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 233 matching lines @@
                 WebInspector.Widget.__assert(this._isRoot, "Attempt to attach widget to orphan node");
         } else if (this._visible) {
             return;
         }
 
         this._visible = true;
 
         if (this._parentIsShowing())
             this._processWillShow();
 
-        this.element.classList.add("visible");
+        this.element.classList.remove("hidden");

[dgozman, 2015/06/09 13:27:02]

Won't this detach iframes?

[pfeldman, 2015/06/09 13:40:59]

Nope, it is alright.

 
         // Reparent
         if (this.element.parentElement !== parentElement) {
             WebInspector.Widget._incrementWidgetCounter(parentElement, this.element);
             if (insertBefore)
                 WebInspector.Widget._originalInsertBefore.call(parentElement, this.element, insertBefore);
             else
                 WebInspector.Widget._originalAppendChild.call(parentElement, this.element);
         }
 
@@ skipping 12 matching lines @@
     detach: function(overrideHideOnDetach)
     {
         var parentElement = this.element.parentElement;
         if (!parentElement)
             return;
 
         if (this._parentIsShowing())
             this._processWillHide();
 
         if (!overrideHideOnDetach && this._shouldHideOnDetach()) {
-            this.element.classList.remove("visible");
+            this.element.classList.add("hidden");
             this._visible = false;
             if (this._parentIsShowing())
                 this._processWasHidden();
             if (this._parentWidget && this._hasNonZeroConstraints())
                 this._parentWidget.invalidateConstraints();
             return;
         }
 
         // Force legal removal
         WebInspector.Widget._decrementWidgetCounter(parentElement, this.element);
@@ skipping 378 matching lines @@
 {
     WebInspector.Widget.__assert(!child.__widgetCounter && !child.__widget, "Attempt to remove element containing widget via regular DOM operation");
     return WebInspector.Widget._originalRemoveChild.call(this, child);
 }
 
 Element.prototype.removeChildren = function()
 {
     WebInspector.Widget.__assert(!this.__widgetCounter, "Attempt to remove element containing widget via regular DOM operation");
     WebInspector.Widget._originalRemoveChildren.call(this);
 }