Implemented URL.canParse() static function for checking if a URL can be
parsed (instead of having to try wrap the constructor).
This avoids using an ErrorResult/Throws, since it is not in the spec,
and this makes it also more performant.
See https://github.com/whatwg/url/pull/763Resolves#2865
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.