This CL adds a context slot to builtin continuation frames which
stores the context, even for stub continuations. This context slot
is used in NotifyDeoptimized to provide the JavaScript context.

Bug: v8:7639
Change-Id: Ibdfe24141a759cda6d319db0933bea57919dc171
Reviewed-on: https://chromium-review.googlesource.com/1002776
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52522}