The ToString intrinsic isn't used anymore, since there is now a ToString
bytecode, so we can remove it.

Change-Id: I5ed121ae4d117660e1ee8a64a2b30e1fb054a886
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2848465
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74151}