SharedFunctionInfos store their original function literal's id. This is
also their index in the Script's SFI list.

Since the function literal id is only needed for lazy compilation and live
edit, we can calculate it on-the-fly by linear search in the Script SFI list,
and save a field on the SFI.

If this regresses compile performance, we could alternatively store the
function literal id on the preparsed scope data as future work.

Bug: chromium:818642
Change-Id: I5468cea0e115921f1c864d94e567d749a4349882
Reviewed-on: https://chromium-review.googlesource.com/1082480
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53523}