Exclude optional features from scores

[SebastianZ]

There are a few optional features like the image-orientation property or the ::search-text pseudo-element.

Such optional features should not count towards the scores.

Sebastian

[LeaVerou]

I think even if a feature is optional, implementing UAs should get a boost. We should definitely mark these in the metadata, and we could later add a user-facing control about whether they are counted in the score.