This bug is just to track the failing test. Note that this test has a warning at the top:
// This test attempts to verify various initial about:blank document
// creation is accurately reflected via the Clients API.  The goal is
// for Clients API to reflect what the browser actually does and not
// to make special cases for the API.
//
// If your browser does not create an about:blank document in certain
// cases then please just mark the test expected fail for now.  The
// reuse of globals from about:blank documents to the final load document
// has particularly bad interop at the moment.  Hopefully we can evolve
// tests like this to eventually align browsers.

We can basically consider this an FYI test and should dig in at some point but P3 for now.