This is a series of tests for checking styles that have sub-styles, or
sub-parts, or whatever the correct name would be; the testing being that if
!important is applied to the whole, that it works.
Starting with #2420 it became apparent that this didn't work as intended,
and once that work started it became obvious that it affected more than just
border.
So these tests test all of the styles that can be specified as a single
whole, or as a set of parts (sides, directions, etc).
