Text spacing rules [24afc2, 78fd32, 9e45ec] incorrectly use "important computed value"

[Jym77]

The Expectation of Letter spacing in style attributes is not !important and other text spacing rules have a first bullet saying:

not important: the computed value of its [text spacing] property is not important; or

This Expectation is needed to handle inherit !important value, where the declaration is important but inherits from a non-important hence overwritable declaration, thus it is not a problem(Passed Example 7).

However, reading the CSS specs, it seems that only declarations are important, not values 🙈
https://github.com/act-rules/act-rules.github.io/pull/1923/files#r1067361598

[carlosapaduarte]

From the CG call:

• Try to update the applicability to remove declaration with inherit; or
• Create a definition for "important" to explain how it gets computed

[dd8]

All computed values have cascade origins, which is the origin of the declared value winning the cascade (which comes from the origin of the style rule containing the declaration) or the origin of the initial value if there were no declared values:

https://drafts.csswg.org/css-cascade/#cascade-sort

The cascade needs to know the origin of each declared value to find the winning declaration. Currently the rule says:

not important: the computed value of its [text spacing] property is not important;

but you could say this instead:

not important: the cascade origin of the computed value of its [text spacing] property is not important;

That should deal with the inherit !important case because the cascade origin is the origin of the inherited value.