This was deleted in 5b2ab2f6, it seems only
the first part of the condition should have been deleted.

This changes (from the embedded builtins):

    movz x9, #0x2
    cmp x9, x8

Back to:

    cmp x8, #0x2

This saves 0.29% in the embedded builtins size for a pointer-compression enabled arm64 build.

Also a minor cleanup by removing the commutative boolean parameter and always commuting the
FlagsContinuation. For a commutative operation the FlagsContinuation will stay the same.

Change-Id: I5bba84a07bb32284b4756bc6293560ee106745f2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762522Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
Cr-Commit-Position: refs/heads/master@{#63337}