Vue 2.7.16-beta.2: More fixes, same energy v2.7.16-beta.2

Another beta drop for the 2.7.x line. We've squashed bugs and polished the rough edges, because Vue 2 isn't going anywhere. Check the changelog for the full list of what got fixed. If you're still running Vue 2 in production (and let's be real, most of us are), this is worth testing.