[1] Add opaque hosts (annevk著, ) <https://github.com/whatwg/url/commit/30362553e9ce9fc706d3492bd61886e399fc94e2>
[2] Allow % and IPv6 addresses in non-special URL hosts (rmisev著, ) <https://github.com/whatwg/url/commit/cdbcce62045b1614695b00cc0427f6fb0fc7ed03>
[3] Attempt to explain valid input better (annevk著, ) <https://github.com/whatwg/url/commit/50cb9ab9d8f70cc2bc72e91976bfaea0ad0fd330>
[4] Add empty host concept for file and non-special URLs (rmisev著, ) <https://github.com/whatwg/url/commit/5807b28261e44a47e31683230137da395ddc79d8>