Do any StyleValue subclasses other than LengthValue need a 'from' method?

[rjwright]

[tabatkins]

LengthValue just has constructors, not a static .from(), right?

Anyway, yeah, all the dimension classes need to have the same constructor/whatever shape.

[shans]

We don't need .from() methods unless there are multiple subclasses of an abstract type base (like LengthValue). So for example CSSAngleValue doesn't need .from() methods.

However we should make sure that there are constructors available for string and calc variants everywhere.

[shans]

CSSNumericValues are now the base of lengths, angles, etc. and have a standard .to() method, so this issue no longer applies.