This cl: https://chromium-review.googlesource.com/c/v8/v8/+/1421077
changed the implementation of SetProperty to infer the language mode.
Language mode is only required when there is an error to decide if we
have to throw an error or not. However we used to compute language mode
eagerly for PropertyCallbackInfo. This causes regressions in some
benchmarks. This cl changes it by deferring it further by computing
it only when it is actually required.

BUG: v8:8580, chromium:925289
Change-Id: Iba70ec5f9bb3deec16414a1ec418b3963f2144f9
Reviewed-on: https://chromium-review.googlesource.com/c/1454608Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59450}