DevTools: introduce dom markers, decorate hidden, forced state and breakpoint elements using marker…

Source/devtools/front_end/components/DOMPresentationUtils.js

 /*
  * Copyright (C) 2011 Google Inc.  All rights reserved.
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
@@ skipping 591 matching lines @@
 WebInspector.DOMNodePathStep.prototype = {
     /**
      * @override
      * @return {string}
      */
     toString: function()
     {
         return this.value;
     }
 }
+
+/**
+ * @interface
+ */
+WebInspector.DOMPresentationUtils.MarkerDecorator = function()
+{
+}
+
+WebInspector.DOMPresentationUtils.MarkerDecorator.prototype = {
+    /**
+     * @param {!WebInspector.DOMNode} node
+     * @return {?string}
+     */
+    decorate: function(node) { }
+}