Currently the shared value barrier manually fast paths instance types
for objects that are always in the shared heap. This CL makes a common
superclass, AlwaysSharedSpaceJSObject, and uses that for the fast path.
Bug: chromium:1402920, v8:12547
Fixed: chromium:1402920
Change-Id: I84421802791a4dc72925341eeb0cfc5949b8938a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4134475
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85192}