Commit 2931348 added EventEmitter#getMaxListeners() but introduced a
regression when people abuse EventEmitter.prototype.on.call() to call
EventEmitter#on() on a non-EE object. Add a workaround for that.
Fixes: https://github.com/iojs/io.js/issues/523
PR-URL: https://github.com/iojs/io.js/pull/527
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>