The actual allocatable size still depends on the allocator;
in particular Blink's ArrayBufferAllocator is currently limited
to 2GB.
WebAssembly memories are not affected by this change (i.e. still
capped at 2GB as well).

For 32-bit platforms, the limit remains at 2**30-1 (=max smi) elements.

Bug: v8:4153
Change-Id: If0d6047dd4061028688d85a3dc0a2684dcca8693
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2007495Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65924}