The type of m is long in 64 bits build, and results implicit conversion
loses integer precision, which was found by improved clang warning
(-Wshorten-64-to-32)

Bug: chromium:1124085
Change-Id: Ic9f22508bd817a06d5c90162b1ac3554a7171529
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2391323
Commit-Queue: Zequan Wu <zequanwu@google.com>
Auto-Submit: Zequan Wu <zequanwu@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69686}