Firefox is incorrectly marked as not supporting starting-style

[jgraham]

web-features thinks that Firefox doesn't support starting-style because BCD has a partial implementation flag for Firefox, on the basis that it doesn't support animating from display:none. However in web-features that functionality is covered by the display-animation feature, and we don't believe it's essential enough to the use cases for starting-style support to be considered blocking.

Based on this we should either update BCD to indicate a full implementation of starting-style, or override the result in web-features.

[captainbrosset]

Three options then:

1. Remove the partial implementation flag from BCD.

   I think this is fair, because BCD already tracks animating from display:none in css.properties.display.is_transitionable and css.properties.display.keyframe_animatable, which our display-animation.yml feature is based on.

2. Do a manual override in web-features.

   To the extent that's possible, we should try to avoid this as it's harder to maintain over time. But it could be, at the very least, a good temporary solution.

3. Split the css.at-rules.starting-style feature in BCD into two parts:

   • One part that records the existence of the property (this one would be supported everywhere)
   • The other part (a subfeature) which records the support for animating from display:none.

Personally, I'd prefer to go with options 1 or 3.

[jamesnw]

I agree that options 1 and 3 would be the best. My leaning is towards #1, but would defer to BCD on what they would prefer.

[captainbrosset]

Thank you, @jgraham, for the BCD fix.
This issue is now fixed with the release of https://github.com/web-platform-dx/web-features/releases/tag/v2.33.0.