This wins us 65 new WPT subtest passes! It also shows up that we're
doing the wrong thing in ShorthandStyleValue in places, notably with
the grid properties. However, having one place to fix instead of two
will make it easier to correct them. :^)
In order to be fully correct, we should use the algorithm here:
https://drafts.csswg.org/cssom/#serialize-a-css-value
However, it's quite hand-wavy. What we do have in the meantime is
`ShorthandStyleValue::to_string()`, where we special-case the
serialization rules for shorthands with a generic fallback that's
equivalent to what the previous `get_property_value()` code was doing.
Implemented by reusing AddMask display list item that was initially
added for `background-clip` property.
Progress on flashlight effect on https://null.com/games/athena-crisis
The CSSOM spec tells us to potentially add up to three different IDL
attributes to CSSStyleDeclaration for every CSS property we support:
- A camelCased attribute, where a dash indicates the next character
should be uppercase
- A camelCased attribute for every -webkit- prefixed property, with the
first letter always being lowercase
- A dashed-attribute for every property with a dash in it.
Additionally, every attribute must have the CEReactions and
LegacyNullToEmptyString extended attributes specified on it.
Since we specify every property we support with Properties.json, we can
use that file to generate the IDL file and it's implementation.
We import it from the Build directory with the help of multiple import
base paths. Then, we add it to CSSStyleDeclaration via the mixin
functionality and inheriting the generated class in
CSSStyleDeclaration.
