We explicitly serialize the backing store when we see the TypedArray.
We then put the reference in the external_pointer. To recalculate the
backing_store pointer during deserialization, we have to keep track of
each TypedArray and then fix up the pointer by adding the offset again.

Bug: v8:6966
Change-Id: I105d44413cffe5766c23c2a3d32ca2b78b5f22e8
Reviewed-on: https://chromium-review.googlesource.com/751269Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49219}