Support for IPv6 addresses

[dapaulid]

Following code:

http.request('http://[::1]:80/foo',function(res) {
    res.on('end', function() {
        console.log('request status: ' + res.statusCode);
    });
}).on('error', function(e) {
       console.log(e.message);
}).end();

will result in this error message:
Failed to execute 'fetch' on 'Window': Failed to parse URL from http://::1:80/foo

The problem seems to be that the implementation is not aware of literal IPv6 addresses in the URL (see https://www.ietf.org/rfc/rfc2732.txt).