When lowering a monomorphic load/store, where multiple receiver maps
have been recorded, but the action to be performed is the same (i.e.
yielding undefined because the property is not found), TurboFan used
to ignore the Smi case, leading to a pretty terrible deoptimization
loop, as the LOAD_IC/STORE_IC properly recorded that state and thus
didn't change it's state.

Fixing this issue gives a 18-20% boost on the prettier test of the
web-tooling-benchmark, which was suffering a lot from this problem.

Bug: v8:6936, v8:6991
Change-Id: Id208ec7129a7f6b190d989bda31f936040393226
Reviewed-on: https://chromium-review.googlesource.com/735342Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48865}