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.
Before, we were using the line height from NodeWithStyle::line_height()
to calculate the y offset for floats inside the IFC. However, this
value doesn't always correspond to the actual height of a line box. For
instance, adding a fragment for an inline-block might change the height
of the line box. With this change, we recalculate the height of the
line box after adding a new fragment and use this recalculated height
value to determine the y position for floats.
Fixes https://github.com/SerenityOS/serenity/issues/20982
