[devtools] Return empty array from DOMNode.children() rather than null.

Source/devtools/front_end/DOMAgent.js

 /*
  * Copyright (C) 2009, 2010 Google Inc. All rights reserved.
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 120 matching lines @@
         return this.value;
     }
 }
 
 WebInspector.DOMNode.prototype = {
     /**
      * @return {Array.<WebInspector.DOMNode>}
      */
     children: function()
     {
-        return this._children ? this._children.slice() : null;
+        return this._children ? this._children.slice() : [];

[pfeldman, 2013/10/09 05:41:06]

This is intentionally null. We should instead do:

children: function()
{
    if (!this._children)
        throw new Error("Requesting children prior to getting them from
backend");
    return this._children;
}

Client should only use this method when they are confident node has already
received children asynchronously and they can proceed with synchronous
operation. This applies to ElementsTreeOutline call sites. If that is not the
case, please file a bug.

     },
 
     /**
      * @return {boolean}
      */
     hasAttributes: function()
     {
         return this._attributes.length > 0;
     },
 
@@ skipping 1583 matching lines @@
     setInspectModeEnabled: function(enabled, inspectShadowDOM, config, callback)
     {
         DOMAgent.setInspectModeEnabled(enabled, inspectShadowDOM, config, callback);
     }
 }
 
 /**
  * @type {?WebInspector.DOMAgent}
  */
 WebInspector.domAgent = null;