[css-properties-values-api] Expand the set of syntaxes for which initial-value is optional #1043
Description
I have lately been using @property a fair bit, and in nearly every real case, I had wished initial-value could have just been automatically set based on my syntax.
There are several cases where there is a very obvious default that works for the vast majority of cases:
<length>:0<number>:0<angle>:0deg<color>:transparent<integer>:0<percentage>:0%<time>:0s<resolution>:0dpi
In my experience, this would simplify over 90% of @property uses.
We discussed making all descriptors optional in #994, but that was mainly centered around inherits. Also, since initial-value is already optional for some cases, maybe it's more acceptable to make it optional for more cases?