Now implemented as a builtin that delegates to the InstanceOfStub. That
stub was parameterized to fallback to either Runtime_InstanceOf or to
Runtime_OrdinaryHasInstance depending on the --harmony-instanceof flag.
Once the feature stabilizes and the flag is no longer needed, we can get
rid of this parameterization again.

R=bmeurer@chromium.org
BUG=v8:4447
LOG=n

Review URL: https://codereview.chromium.org/1819813002

Cr-Commit-Position: refs/heads/master@{#34959}