(In reply to Henri Sivonen (:hsivonen) from comment #0)
https://searchfox.org/mozilla-central/source/layout/base/tests/test_bug842853-2.html fails in Fission with the patch for bug 1663931. The root cause appears to be the processing of
location.reload() has become asynchronous while the test expects the
location.reload() to abort the document synchronously and, therefore, to cause the
load event not to fire for the load during which
location.reload() was called.
As far as I can tell, the spec does require us to abort pending document load before we return from
reload(), but it doesn't look like we currently do that either with or without SHiP. It also doesn't appear to cause the test to fail.
verifyAfterLoad() is just called for the load event of the initial document and successfully ends the test without ever testing that the scroll positions are preserved after the reload.