Add new appNotifications permission to built-in webstore app

This is so we can use the webstore app for dogfood experiments.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/8771045

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112813 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/webstore_app/manifest.json

@@ -14,6 +14,7 @@
     ]
   },
   "permissions": [
+    "appNotifications",
     "webstorePrivate",
     "management"
   ]