Currently, if input types are not string or number, ToString builtin
will fall into runtime and a loop of ToPrimitive and type-checks is
done in runtime, which is slow.

This CL reimplements ToString to add support for that ToPrimitive and
type-checks loop in CSA instead of runtime to improve performance. This
will benefit Array.prototype.toString/join a lot when the array elements
are objects.

This Cl improves the performance of Speedometer2.0 EmberJS-Debug case
by ~14% on Atom.

Change-Id: I27c2669097be1e542e30119cdffcf79c0d16a0eb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1498698
Commit-Queue: Shiyu Zhang <shiyu.zhang@intel.com>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60144}