Remove obsolete definitions from macros.py, and drop the now obsolete
%_ToPrimitive, %_ToPrimitive_Number, %_ToPrimitive_String, %_ToName
and the %ToPrimitive_String intrinsics/runtime entries.

R=yangguo@chromium.org
BUG=v8:5049

Review-Url: https://codereview.chromium.org/2137203002
Cr-Commit-Position: refs/heads/master@{#37665}