This CL restores special crankshaft optimizations for instance of when
--harmony-instanceof is true. Similar work has to happen for TurboFan.

I've added a flag to pile-up the optimizations to be done elsewhere, which
will follow over several CLs.

R=verwaest@chromium.org, mstarzinger@chromium.org
BUG=v8:4447
LOG=n

Review URL: https://codereview.chromium.org/1809113002

Cr-Commit-Position: refs/heads/master@{#34930}