Clang is known to use a lot of stack space for Debug builds, so
this patch lowers the recursion depth of that test after recent
changes made Debug-mode stack frames a bit larger.

a bit of Debug-mode stack space.

Bonus: drops an unnecessary cast from SerializeJSObject to save
Change-Id: I22696a1d80a6a73b5049b018e72cc8a3d8693042
Reviewed-on: https://chromium-review.googlesource.com/c/1334448Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57516}