Add SetProperties as the generic interface to set properties. In the
future, this will switch based on the input properties type and
correctly store the hash code.

This patch also updates tests to check against empty_property_array
instead of empty_fixed_array.

Bug: v8:6404
Change-Id: I39d324ea3ab3cc2c2223b6f4be64139bb88edd94
Reviewed-on: https://chromium-review.googlesource.com/574761Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46744}