Some string constant optimizations in JSNativeContextSpecialization
assumed an incorrect maximal string length of double values.

Bug: chromium:1189077, chromium:1178718
Change-Id: Iae531f0e323679a4490e666a971b66655c25c757
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2843361
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74101}