Always set addEventListener and removeEventListener useCaption flag

If this flag is not set (false by default), ```NS_ERROR_XPC_NOT_ENOUGH_ARGS``` are getting raised on old browsers such Firefox 5.

For more details about this flag:
> useCapture became optional only in more recent versions of the major browsers; for   example, it was not optional prior to Firefox 6. You should provide that parameter for broadest compatibility.
https://developer.mozilla.org/en/docs/DOM/element.addEventListener