The CallICStub has call-site specific knowledge about the receiver,
which we did not utilize; plus the CallICStub does in some case know
whether it is about to [[Call]] a function or potentially some other
callable. In the common case we actually know that the target is a
function and so we can use the CallFunction builtin directly instead
of redispatching in the Call builtin.

BUG=chromium:555127, v8:4413
LOG=n

Review URL: https://codereview.chromium.org/1470803002

Cr-Commit-Position: refs/heads/master@{#32163}