[css-properties-and-values-api] should initial values be allowed to have variable references?

[heycam]

What would it mean for a custom property's initial value to have a variable reference in it? It doesn't sound useful. Should it make registerProperty throw an exception?

[shans]

in general, values that can't be directly represented as computed values seem weird. For example, specifying '4em' as an initial value would mean that:

(1) if the property is not inherited then it would need to compute 4em for every element
(2) if the property is inherited then the root would compute a result for 4em and the result would
be inherited down the tree.

[shans]

See also #122

[tabatkins]

Fixed in 321c596. var() isn't allowed, because it's not computationally idempotent (and I defined what that actually means).