Re: Add direction-specific pan values to touch-action?

That's a good question.  I think what matters for touch-action is the
co-ordinate space of the input events.  Since those don't invert in RTL
then I think we'd really want true right/left here.  The logic for chaining
correctly with a native scroller would probably be non-trivial, but I doubt
we could reasonably simplify this (RTL is hard).
Would left and right be reversed if the page language is right-to-left? Or
would the CSS potentially need to change based on the language? I'm not
familiar with whether gestures like that are reversed in languages like
Arabic, or perhaps the use cases don't require it.