Add support to optimize certain comparisons of typeof with known
strings to utilize the existing ObjectIs<Type> predicates. Also
add a new ObjectIsCallable, which is used to optimize the common
typeof x === "function" pattern.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1898653003

Cr-Commit-Position: refs/heads/master@{#35562}