[DevTools] JSONView parsing smarter

third_party/WebKit/Source/devtools/front_end/es_tree/ESTreeWalker.js

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
- * @param {function(!ESTree.Node)} beforeVisit
+ * @param {function(!ESTree.Node):(!Object|undefined)} beforeVisit
  * @param {function(!ESTree.Node)=} afterVisit
  */
 WebInspector.ESTreeWalker = function(beforeVisit, afterVisit)
 {
     this._beforeVisit = beforeVisit;
     this._afterVisit = afterVisit || new Function();
+    this._walkNulls = false;
 }
 
+/** @typedef {!Object} WebInspector.ESTreeWalker.SkipSubtree */
 WebInspector.ESTreeWalker.SkipSubtree = {};
 
 WebInspector.ESTreeWalker.prototype = {
     /**
+     * @param {boolean} value
+     */
+    setWalkNulls: function(value)
+    {
+        this._walkNulls = value;
+    },
+
+    /**
      * @param {!ESTree.Node} ast
      */
     walk: function(ast)
     {
         this._innerWalk(ast, null);
     },
 
     /**
      * @param {!ESTree.Node} node
      * @param {?ESTree.Node} parent
      */
     _innerWalk: function(node, parent)
     {
+        if (!node && parent && this._walkNulls) {
+            node = /** @type {!ESTree.Node} */ ({
+                type: "Literal",
+                raw: "null",
+                value: null
+            });
+        }
+
         if (!node)
             return;
         node.parent = parent;
 
         if (this._beforeVisit.call(null, node) === WebInspector.ESTreeWalker.SkipSubtree) {
             this._afterVisit.call(null, node);
             return;
         }
 
         var walkOrder = WebInspector.ESTreeWalker._walkOrder[node.type];
@@ skipping 80 matching lines @@
     "ThrowStatement": ["argument"],
     "TryStatement": ["block", "handler", "finalizer"],
     "UnaryExpression": ["argument"],
     "UpdateExpression": ["argument"],
     "VariableDeclaration": ["declarations"],
     "VariableDeclarator": ["id", "init"],
     "WhileStatement": ["test", "body"],
     "WithStatement": ["object", "body"],
     "YieldExpression": ["argument"]
 }