Add support for keyword values for min-width and max-width
This is a follow-up to #14432 which got closed and can no longer be re-opened.
This PR aims to add support for keyword-values max-content, min-content, fit-content, and fill-available to the properties that use them, namely min-width, min-height, max-width, and max-height.
It's still untested because I still haven't figured out how to do that. I guess I should write or find some web page that uses these properties.
Refs #13821.
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Implement an ExtremumLength type which contains all the enumerated
keyword values for min-width, min-height, max-width, and
max-height. Then, implement a MinLength which can be used for min-width
and min-height. So far this just maps to Gecko values.
Refs #13821.
fix test-tidy errors
fix style unit test
use the Parse trait instead of ParseWithContext
fix stylo test and geckolib build
move all specified url parse code to parse trait and remove refs to unused type
This patch introduces infrastructure for the rule tree, and constructs it.
We don't use it yet, nor have good heuristics for GC'ing it, but this should not
happen anymore once we store the rule node reference in the node.
I haven't messed up with memory orders because I want to do a try run with it,
then mess with them.
Take down the ApplicableDeclarationsCache, use the rule tree for doing the cascade.
Use enum BorderWidth instead of a tuple-like struct to store the specified
value. BorderWidth is needed to be used in both longhand and shorthand
border width properties, so I put it in `specified` module.
Fixed#13869.
Expressions with percentages may be negative or positive at computed value time.
So, we can only clamp lengths at computed value time, which is what the other
browsers do.
