Since we only ever have preparsed scope info data for functions that
haven't been parsed yet, it never overlaps with there being other
function data (such as a bytecode array). So, we can merge the two
fields.

This drops the SharedFunctionInfo size by one pointer.

Bug: chromium:783853
Change-Id: I7166010271cf661b04d3d118ac87c65c79555f96
Reviewed-on: https://chromium-review.googlesource.com/774863Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49445}