The isolate snapshot must not contain context-dependent objects, thus
root visitation must not reach context-dependent objects. This CL
sanitizes the isolate around serialization by clearing & later
restoring two lists: 1. feedback vectors for profiling tools, 2.
detached contexts.

Drive-by: Set an array buffer allocator for
SerializeDeserializeAndVerify.
Drive-by: Allow serialization of *another* native context when
serializing a native context.

Bug: v8:10416,v8:10493
Change-Id: I1c49bda364eccd6d44f9499a9926f4bcd31f665d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2179008Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67584}