When this flag is enabled, allocation folding behaviour depends
on the --turbo-allocation-folding runtime flag.

When it's disabled, --turbo-allocation-folding is ignored.

This flag will be used later to control the
CodeStubAssembler::InlineAllocate behaviour.

Change-Id: Iea7bbafd8454571dda7d56349b3dc63d3b54ba99
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2878754Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Wenyu Zhao <wenyu.zhao@anu.edu.au>
Cr-Commit-Position: refs/heads/master@{#74858}