Per suggestion, we put this behind runtime flag in the mean time.
Refactor some codes.

Bug: v8:6831
Change-Id: Ibeb2a62b2a132971f8bc51c045bf0d2594eec198
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1566238
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60927}