We need some Ahem versions of these tests to check that, assuming
font-size: 1px; font-size-adjust: 8, the following all come out as
exactly the same size:

   line-height: 2;
   line-height: 2em;
   line-height: 200%;
   line-height: 20px;

   border: 20px;

Also we need checks that font-size inherits the computed value not the
actual value, and all the existing tests need Ahem versions for QA.