RE: Proposal for changes to manage Shadow DOM content distribution

[Domenic Denicola]

Between content-slot-specified slots, attribute-specified slots, element-named 
slots, and everything-else-slots, we're now in a weird place where we've 
reinvented a micro-language with some, but not all, of the power of CSS 
selectors. Is adding a new micro-language to the web platform worth helping 
implementers avoid the complexity of implementing CSS selector matching in this 
context?