postcss-hwb-function

[romainmenke]

see : #70

splitting that one in smaller bits for easier review

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prior work : https://github.com/postcss/postcss-color-hwb

This plugin differs in that it does not accept comma separated values:
hwb(90, 0%, 0%, 0.5);

That notation is not covered by the latest spec.

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This change adds only hwb().

Largely follows the methods in lab and functional-color-notation.

[Antonio-Laguna]

Impressive as usual!

Do you plan to enable this too for 7.3?

[romainmenke]

Would be great if we can include this in 7.3!