This is just to make the CSS parser stop whining when it encounters some
very common properties and identifiers. More work will be required to
actually support these things. :^)
Two CSS quirks are specced to only apply to specific properties:
- The hashless hex color quirk
https://quirks.spec.whatwg.org/#the-hashless-hex-color-quirk
- The unitless length quirk
https://quirks.spec.whatwg.org/#the-unitless-length-quirk
These are now represented in `Properties.json` like so:
```json
"property-name-here": {
"quirks": [
"hashless-hex-color",
"unitless-length"
]
}
```
Every property that either of those two quirks applies to is included in
`Properties.json` and now has their quirks listed. :^)
We already include the inheritance for each property in Properties.json,
so made sense to use that instead of a list in StyleResolver.
Added `inherited: true` to a couple of properties to match the previous
code's behavior. One of those had a FIXME which I've moved to the JSON
file, which is hacky, but it works.
The background-repeat value may be specified as either one- or two-value
identifiers (to be interpreted as horizontal and vertical repeat). This
adds two pseudo-properties, background-repeat-x and background-repeat-y,
to handle this. One-value identifiers are mapped to two-value in
accordance with the spec.
