There are likely cleanups that can be done after this CL:
- context-related functions in the interpreter and compiler take ScopeInfo as
well as ScopeType and slot-count as input. The latter 2 should be directly
derived from the former. We should be able to drop FunctionContextParameters.
- ContextExtension is probably not needed anymore, since we now always have the
correct scope_info directly in the SCOPE_INFO_INDEX slot.

Bug: v8:7066
Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ie1f6134c686a9f2183e54730d9cdd598a9e5ab67
Reviewed-on: https://chromium-review.googlesource.com/785151
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52952}