Upstream tests to web-platform-tests

[foolip]

There are tests in https://github.com/WICG/InputDeviceCapabilities/tree/gh-pages/tests

The string "firesTouchEvents", "pointerMovementScrolls" and "sourceCapabilities" never appear in wpt, so there probably aren't any tests there.

Picking a directory name will be fun, see WICG/admin#42 :)