Thanks for looking into it, for reference the documentation notes that it is only available through OS X 10.9, see https://developer.apple.com/library/mac/documentation/AppKit/Reference/NSTouch_Class/#//apple_ref/occ/instp/NSTouch/isResting which is as official as it gets with Apple.

I can confirm that as of OS X 10.10.2 (14C81f) and possibly earlier versions this crash no longer happens since the param was restored, presumably to prevent too many old(er) apps from crashing. As I mentioned in the report It's still a good idea to fix it if at all possible. Thanks!