Allow one line blocks

[delapuente]

From time to time you simply need to remove or leave debug traces or performance marks. For these cases, an alternative syntax to make the directive affect only the next line or the next block would be great. I suggest extending syntax to allow affect next line (_) or block ({}):

// @ifdef DEBUG {}
function debug(msg) {
  console.log('[DEBUG] ' + msg)
}

// @ifdef DEBUG _
debug('A trace!');