On 64-bit platforms we reserve the maximum size of a WebAssembly memory.
Thereby the memory can grow in-place. On 32-bit platforms, however, we
allocate only the initial size, and grow the memory by reallocating the
memory. Due to memory fragmentation the memory therefore cannot grow
big. With this CL we allow to reserve 1GB of memory even on 32-bit
platforms. Thereby the memory can grow to at least 1GB.

R=gdeepti@chromium.org
CC=ulan@chromium.org

Bug: chromium:1175564
Change-Id: Iba44bb64ffa47322a205e8da3b7088e3edfeee62
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2707163Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72888}