Callables for TF builtins are autogenerated and accessible through
Builtins::CallableFor.  This removes the manually written accessors from
CodeFactory.

Bug: v8:6474,v8:5737
Change-Id: I9d8dec97995471c1bb258147220c190bf72e5de8
Reviewed-on: https://chromium-review.googlesource.com/530745Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45839}