These are used to check for Smi or HeapObject, and we use them
appropriately in JSNativeContextSpecialization, so we don't need
to introduce dependencies on concrete control flow and/or concrete
frame states.

They will be optimized by a proper check elimination reducer,
which will be added in a separate CL.

R=jarin@chromium.org
BUG=v8:4470

Review-Url: https://codereview.chromium.org/2082523002
Cr-Commit-Position: refs/heads/master@{#37096}