This means ReadOnlyDeserializer can be made isolate independent. Without
this Isolate is needed for rehashing read-only space.


Bug: v8:7464
Change-Id: Id2c9968a0ecfa2362f499ded6c7e0f7b2be00dfb
Reviewed-on: https://chromium-review.googlesource.com/c/1483054
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59823}