Adjust format type and add serialize type test.

[jgerigmeyer]

This adds a type test for the change in d0ab5d1, and also adjusts the Format type to account for the change in 667c19a.

[LeaVerou]

Thanks! LGTM, though I'm thinking of renaming noAlpha to opaque or opaqueOnly since negative names are an API design antipattern. Though "opaque" is a more obscure word, and that's also an antipattern. 🤔

[jgerigmeyer]

Thanks! LGTM, though I'm thinking of renaming noAlpha to opaque or opaqueOnly since negative names are an API design antipattern. Though "opaque" is a more obscure word, and that's also an antipattern. 🤔

Maybe includeAlpha and default to true?

[LeaVerou]

Thanks! LGTM, though I'm thinking of renaming noAlpha to opaque or opaqueOnly since negative names are an API design antipattern. Though "opaque" is a more obscure word, and that's also an antipattern. 🤔

Maybe includeAlpha and default to true?

Booleans that default to true is another API Design antipattern, possibly a bigger one…