Revert 136296 - Make all extension api types fully qualified.

chrome/common/extensions/api/extension.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": "extension",
     "nocompile": true,
     "dependencies": [ "tabs" ],
     "types": [
       {
         "id": "MessageSender",
         "type": "object",
         "description": "An object containing information about the script context that sent a message or request.",
         "properties": {
-          "tab": {"$ref": "tabs.Tab", "optional": true, "description":"This property will <b>only</b> be present when the connection was opened from a tab or content script."},
+          "tab": {"$ref": "Tab", "optional": true, "description":"This property will <b>only</b> be present when the connection was opened from a tab or content script."},
           "id": {"type": "string", "description": "The extension ID of the extension that opened the connection."}
         }
       },
       {
         "id": "Event",
         "type": "object",
         "description": "An object which allows the addition and removal of listeners for a Chrome event.",
         "properties": {
           "addListener": {"type": "function"},
           "removeListener": {"type": "function"},
@@ skipping 310 matching lines @@
         ],
         "returns": {
           "type": "boolean",
           "optional": "true",
           "description": "Return true from the event listener if you wish to call <code>sendResponse</code> after the event listener returns."
         }
       }
     ]
   }
 ]