Remove (for now) tentative accname tests conflicting with current spec
This change drops two subtests from the tentative accname test at
accname/name/comp_name_from_content.tentative.html. Gecko, WebKit, and
Chromium all fail those, and the tests don’t conform to the current spec
requirements, nor to any WIP PR for changing the spec requirements. And
there seems to have been no indication so far from Gecko, WebKit, or
Chromium that they’re interested in implementing the change that’d be
required to get their implementations passing those tests.
So let’s remove them for now. If circumstances change, we can add them
back later.