Auto merge of #141678 - Kobzol:revert-141516, r=workingjubilee

Revert "increase perf of charsearcher for single ascii characters"

This reverts commit 245bf503e2a948ac98170516d11df632e85a948b (PR rust-lang/rust#141516).

It caused a large `doc` perf. regression in rust-lang/rust#141605.

Author: bors