This slightly generalizes the current mechnanism for property loads to
also deal with property stores (both monomorphic and polymorphic). It's
still somewhat adhoc, but it already handles a lot of the interesting
cases. We might want to wait for keyed accesses before we start
refactoring to a more general solution.

R=jarin@chromium.org
BUG=v8:4470
LOG=n

Review URL: https://codereview.chromium.org/1422573002

Cr-Commit-Position: refs/heads/master@{#31475}