This is a part of refactoring towards making the paintable tree
independent of the layout tree. Now, instead of transferring text
fragments from the layout tree to the paintable tree during the layout
commit phase, we allocate separate PaintableFragments that contain only
the information necessary for painting. Doing this also allows us to
get rid LineBoxes, as they are used only during layout.
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.
The styling of elements using the `use_pseudo_element()` was only
applied on layout. When an element style was recomputed later that
styling was not overruled with the pseudo element selector styles.
This moves the styling override from `TreeBuilder.cpp` to
`StyleComputer.cpp`. Now the styles are always correctly applied.
I also removed the method `property_id_by_index()` because it was
not needed anymore.
Als some calls to `invalidate_layout()` in the Meter, Progress and
Select elements where not needed anymore because the style values
are update on the changing of the style attribute.
This fixes issue #22278.
