Allow comments in extension config files.

chrome/common/extensions/api/devtools.json

+// Copyright (c) 2012 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.
+
 [
   {
     "namespace": "devtools",
     "nodoc": "true",
     "types": [],
     "functions": [
       {
         "name": "getTabEvents",
         "type": "function",
         "description": "Experimental support for timeline API",
         "nodoc": "true",
         "parameters": [
           {
             "name": "tab_id",
             "type": "integer"
           }
         ],
         "returns": {
           "type": "object",
           "additionalProperties": { "type": "any" },
           "description": "DevTools tab events object"
         }
       }
     ]
   }
 ]