new inference: infer from return value from method ref
RootIndex: less vfs lookups when searching for non-existing packages, don't cache empty results
Fix  OC-5992 Formatter:  PsiComment.BlockFormatting ->PsiDocCommentBase   +review CR-OC-1034
ThreadFactory.newThread() is allowed to return null
http://ea.jetbrains.com/browser/ea_problems/49730