Avoids allocating a frame for the fast-path in IncHandler by marking some calling
branches as Deferred. Also avoid loading feedback slot and vector until it's needed
to reduce live range.

This reduces the time needed for a tight loop in Ignition (e.g.,
while (i < 1000000000) ++i;) from 15.5s to 12.8s.

BUG=v8:9133

Change-Id: I0a62efdaefca7f3024b3ae05c61631a63cb01390
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1570005
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60893}