We only use the safe math helpers (CheckedNumeric<T>) in very few
places. The headers are huge though, and complex. They are pulled in to
839 of our object files, increasing compilation time.

I also find the implicit checks more easy to understand than the complex
logic in CheckedNumeric.

Thus, this CL removes the safe_math headers and implements bounds
checks for the five uses explicitly.

R=jkummerow@chromium.org, mlippautz@chromium.org

Bug: v8:8834
Change-Id: I2d60f95799ee61cfa161354428605f67829cd736
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1547651Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60630}