inform about minifiers and IE<9

Every minifier I know automatically wraps in strings ES3 reserved words when it comes to property access.  `obj.delete`, `obj.default`, `obj.catch`, these are always wrapped as `obj["delete"]`,  `obj["default"]`,  `obj["catch"]` and every other so IE<9 is a non real-word/production concern at all ( assuming developers will use minifiers and they should anyway )