ObjectView abstracts Start/End/Size of an object over the different
internal representations (HeapObjectHeader and LargePage).

Bug: chromium:1056170
Change-Id: I4e888f907fff94c1b02d5e21b4ec3f4a78a471f8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2892081
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74594}