Note that using `servo --devtools http://example.org` doesn't work. In
that case either the port must be specified or the option moved to the
end. This is done by getopts and is the same for other such options,
e.g. `--profile`.
… when parsing as an absolute URL (without a base) fails.
Previously, arguments were parsed as URLs with the current working directory
converted to an URL and used as the base URL. This mostly worked for
relative filenames, except that `?` and `#` had a special meaning
and needed to be percent-encoded.
Fix#3340.
