Test Location sans browsing context

[annevk]

For whatwg/html#3959.

[foolip]

Reviewed for test structure and general reasonableness of what is being asserted, but please name .tentative. if this is merged before the spec change. (Doing that might make it easier to see cross-browser results.)

[domenic]

Tests seem good but I have a readability improvement I'd really like to see if possible :)

[domenic]

This is pretty hard to read. It's more work for you but I'd suggest

[
  {
    prop: "href",
    expected: "about:blank",
    valuesToTry: ["https://example.com/", "/", "http://test:test/", "test test", "test:test", "chrome:fail"]
  },
  ...
}