template specialisations must be defined
outside of class body to prevent the following compilation error:

error: explicit specialization in non-namespace scope

Change-Id: Ic4b74a28cd21d96991ad784fbd3c598668ffc476
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3129881Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#76591}