Merge the outer_scope_info and feedback_metadata fields on
SharedFunctionInfo. outer_scope_info is only used during parsing,
and feedback_metadata is only available after compilation, so the
two never exist at the same time. Thus, they can share a field slot.

The exception is un-compiling and re-compiling a function, where we
need the outer_scope_info again. Fortunately, the outer_scope_info
can be re-calculated from the SFI's scope_info.

Bug: v8:7606
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I6b97fefe859e89df75ad870da4a0bfa4b869772a
Reviewed-on: https://chromium-review.googlesource.com/992432Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52454}