DevTools: measure should not destroy elements hierarchy.

third_party/WebKit/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 442 matching lines @@
         var activeElement = this.element.ownerDocument.activeElement;
         return activeElement && activeElement.isSelfOrDescendant(this.element);
     },
 
     /**
      * @return {!Size}
      */
     measurePreferredSize: function()
     {
         var document = this.element.ownerDocument;
+        var oldParent = this.element.parentElement;
+        var oldNextSibling = this.element.nextSibling;
+
         WebInspector.Widget._originalAppendChild.call(document.body, this.element);
         this.element.positionAt(0, 0);
         var result = new Size(this.element.offsetWidth, this.element.offsetHeight);
+
         this.element.positionAt(undefined, undefined);
-        WebInspector.Widget._originalRemoveChild.call(document.body, this.element);
+        if (oldParent)
+            WebInspector.Widget._originalInsertBefore.call(oldParent, this.element, oldNextSibling);
+        else
+            WebInspector.Widget._originalRemoveChild.call(document.body, this.element);
         return result;
     },
 
     /**
      * @return {!Constraints}
      */
     calculateConstraints: function()
     {
         return new Constraints();
     },
@@ skipping 307 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);
 }