This extends the existing insertion of soft deopts during early lowering
from named loads to keyed loads as well (i.e. from just {JSLoadName} to
{JSLoadProperty}). Stores will be handled in a follow-up change.

R=bmeurer@chromium.org

Change-Id: I6ad7d0a3561f9160e15e13c64ec5255b4f45e614
Reviewed-on: https://chromium-review.googlesource.com/459421Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44187}