Track only the number of important declarations in a declaration block

[emilio]

Once #12943 lands, DeclarationBlock will have two fields, normal_count and important_count that track the amount of declarations with a given priority are in that block.

We should be able to remove one of the two fields, and compute the other one in terms of the length of the declarations vector and the other, simplifying the code that computes it.

Code:

• components/style/properties/properties.mako.rs

Tests:

• No need to write new ones, the existing tests should cover it. You'll have to modify test/units/style to take the change into account.

[highfive]

Please make a comment here if you intend to work on this issue. Thank you!

[SimonSapin]

Run ./mach test-unit to try changes to tests/unit.

[cers]

I'd like to give it a go, but this would be my first foray into servo (and indeed rust).

Should the field be removed completely, or should the calculation of it just be moved to the end of the parsing, when it can be calculated by subtracting the important ones from the total?

If completely removed, then I guess some consideration is needed to components/script/dom/element.rs and components/style/selector_matching.rs, which both seem to reference the normal_count of a style rule/block.

[emilio]

Sure, it's yours! :)

Yes, the idea is removing it completely, and yes, the calculations in element.rs and selector_matching.rs should be modified appropriately.

If you have any more doubts, don't hesitate in reaching out :)