date in Makeday should be converted to integer.
https://www.ecma-international.org/ecma-262/5.1/#sec-15.9.1.12

Bug: v8:7475,chromium:846723
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I3aa725e7ce1822345502284aec919695c4ca084d
Reviewed-on: https://chromium-review.googlesource.com/1080110
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53516}