We currently have a handful of iframe tests whose sources are in the
"input" directory. This means they get run as their own tests, when they
are really just helper files. We've had to add empty test expectation
files for these "tests", and invoke a dummy test() method just to keep
the test runner happy.
Instead, move them to their own directory so the test runner does not
see them at all.
This patch makes a few changes to the way we calculate line-height:
- `line-height: normal` is now resolved using metrics from the used
font (specifically, round(A + D + lineGap)).
- `line-height: calc(...)` is now resolved at style compute time.
- `line-height` values are now absolutized at style compute time.
As a consequence of the above, we no longer need to walk the DOM
ancestor chain looking for line-heights during style computation.
Instead, values are inherited, resolved and absolutized locally.
This is not only much faster, but also makes our line-height metrics
match those of other engines like Gecko and Blink.
