It's not possible to correctly determine during the css cascade whether the container height
is explicitly specified. Additionally, the spec https://drafts.csswg.org/css2/visudet.html#the-height-property
says this should affect the *used* height, rather than the computed height.
This significantly improves the layout in #6643.
This commit introduces the `serde` dependency, which we will use to
serialize messages going between processes in multiprocess Servo.
This also adds a new debugging flag, `-Z print-display-list-json`,
allowing the output of display list serialization to be visualized.
This will be useful for our experiments with alternate rasterizers.
This fixes layers being created with a 3x3 border that's not needed.
This exposes https://github.com/servo/servo/issues/6250, so update the affected reftest to use ahem font until it is fixed.
Known issues:
* Collapsed borders do not correctly affect the border-box of the table
itself.
* The content widths of all cells in a column and the content height of
all cells in a row is the same in this patch, but not in Gecko and
WebKit.
* Corners are not painted well. The spec does not say what to do here.
* Column spans are not handled well. The spec does not say what to do
here either.
`FontContext::get_layout_font_group_for_style()`.
There are several optimizations here:
* We make font families atoms, to allow for quicker comparisons.
* We precalculate an FNV hash of the relevant fields of the font style
structure.
* When obtaining a platform font group, we first check pointer equality
for the font style. If there's no match, we go to the FNV hash. Only
if both caches miss do we construct and cache a font group. Note that
individual fonts are *also* cached; thus there are two layers of
caching here.
15% improvement in total layout thread time for Facebook Timeline.
Transition events are not yet supported, and the only animatable
properties are `top`, `right`, `bottom`, and `left`. However, all other
features of transitions are supported. There are no automated tests at
present because I'm not sure how best to test it, but three manual tests
are included.
