fix compilation for usage in Kotlin file

PSI invalidation should be O(number of present PsiFiles), not O(maximum number of PsiFiles ever created)

otherwise we get thread dumps where EDT spends time in ConcurrentHashMap.clear

use ActionPromoter instead of relying on order of entries in XML files
(following IDEA-CR-29068)

Fix synthetic return types, drop unused code

fix test cases

Vitaly Provodin

otherwise it's irritating to switch between two styles of method call insertion