With lazy deserialization, the target code object may have been replaced
by DeserializeLazy. In that case, we can get the target builtin id from
the shared function info, and we need to skip RelocInfo iteration (it
doesn't exist yet).

Bug: v8:6624
Change-Id: I765b74de313e65bfdf0122f13535029994fc0de1
Reviewed-on: https://chromium-review.googlesource.com/655159Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47878}