Make Servo's rounding of image-orientation values agree with Gecko's, and pass orientations directly as an enum instead of as angles.
Has been reviewed: https://reviewboard.mozilla.org/r/155336/
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Bugzilla issue: https://bugzilla.mozilla.org/show_bug.cgi?id=1355380
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selectors: Avoid looking at MatchingMode if the selector isn't the topmost.
Also, switch the hover quirk to the same mechanism.
Bug: 1379696
Reviewed-By: bholley
MozReview-Commit-ID: KrmNqNyASf6
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Store font-weight as integer directly
It doesn't make much sense to store `font-weight` as separate enums, especially given that we would need to support (somehow) arbitrary font weight value when we implement CSS Fonts Level 4.
This PR refactors the `font-weight` a bit to make it store as `u16` directly.
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stylo: Fix font-variant-alternates property
`font-variant-alternates` was just parsing values as keywords. But many of the alternates are actually functions instead of keywords. This fixes that.
r=emilio on bugzilla side.
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stylo: Implement font-language-override descriptor for @font-face rule
Generally we use computed values for `@font-face` rule descriptors but that descriptor is a bit different than the others in gecko side. It accepts strings instead of unsigned integer(which is computed value of this property). So we had to use SpecifiedValue for that in here.
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