Remove %ToPrimitive, %ToPrimitive_Number, %SameValue and %SameValueZero,
as these runtime functions were only used from tests. For the %SameValue
we use Object.is() to test the internal algorithm (the actual one even),
and for %SameValueZero we use Set#has() - this was already the case for
most uses anyways.

Also drop %IsDate and %ValueOf, which didn't have uses at all.

Bug: v8:8015
Change-Id: Ice26d25e68aed4d5d8adac0547c56aedf9826b13
Reviewed-on: https://chromium-review.googlesource.com/1237677
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56127}