We now only require API references to be provided when we
actually deserialize them. Also changed the internal implementation
to avoid copying API references into V8.

R=petermarshall@chromium.org

Bug: v8:6448
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Iddb0465ff6e95020006d41b5e87614dce8f0140b
Reviewed-on: https://chromium-review.googlesource.com/632098Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47649}