With a recent change we reserve the maximum memory size also on 32-bit
platforms, up to 1GB. This change, however, caused failing tests in the
cases where no maximum memory size was defined and where WebAssembly
defines an implicit maximum memory size of 4GB. With this CL we do not
reserve more memory than the initial size if no maximum memory size is
defined.

R=clemensb@chromium.org

Bug: v8:11493
Change-Id: I62b62fd4faa7a480275b75421a98f73539646eab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2712756
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72977}