bytes, strings: restore O(1) behavior of IndexAny(s, "") and LastIndexAny(s, "")
CL 65851 (bytes) and CL 65910 (strings) “improve[d] readability”
by removing the special case that bypassed the whole function body
when chars == "". In doing so, yes, the function was unindented a
level, which is nice, but the runtime of that case went from O(1) to O(n)
where n = len(s).
I don't know if anyone's code depends on the O(1) behavior in this case,
but quite possibly someone's does.
This CL adds the special case back, with a comment to prevent future
deletions, and without reindenting each function body in full.