Text marks do not support stroke and strokeOpacity as channels. #467
Description
stroke and strokeOpacity are documented as standard mark channels, but they are not supported on text marks. (Related, rules also do not yet support strokeOpacity as channel #466, and in the near future, strokeWidth may become a standard mark channel #311.)
My inclination is that we should probably support these as channels on text marks, even if they will almost never be used; alternatively, we could explicitly call out in the documentation that these standard channels are not supported on text marks, but that would leave a gotcha for anyone who doesn’t exactingly read the full documentation.