HHVM failing to parse some valid data: URI

With PHP:

```
php > echo file_get_contents('data:text/plain;charset=utf-8;base64,SGVsbG8gV29ybGQh');
Hello World!
```

With HHVM:

```
hphpd> echo file_get_contents('data:text/plain;charset=utf-8;base64,SGVsbG8gV29ybGQh');
echo file_get_contents('data:text/plain;charset=utf-8;base64,SGVsbG8gV29ybGQh');

Warning: rfc2396: invalid parameter
```

Reproduce the PHP and HHVM commands from the issue, then trace the file_get_contents handling for data: URIs and the rfc2396 parameter parser. Done means HHVM accepts this valid base64 data URI and returns "Hello World!" without the warning.

Written by the indexing model from the issue text.