UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36

Steps to reproduce the problem:
`new URL('ssh://github.com/test/repo.git')` 

What is the expected behavior?
The URL object should have `hostname` "github.com" and `pathname "/test/repo.git" according to the spec.

What went wrong?
The URL object has `hostname` "" and `pathname` "//github.com/test/repo.git".

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 70.0.3538.77  Channel: stable
OS Version: OS X 10.14.0
Flash Version: 

Repro website: https://felixfbecker.github.io/whatwg-url-custom-host-repro/
Filed on https://github.com/webcompat/web-bugs/issues/19792
Specific test case added in https://github.com/web-platform-tests/wpt/pull/13516 (although also already covered in existing tests)

Chrome and Firefox both misbehave, while Edge, Safari, Node and whatwg-url behave spec-compliant.

This makes the URL API unreliable to use for generic URL parsing and always requires us to polyfill it (which is pretty big).