For JSCreate nodes with constant inputs we cannot simply assume that the
new.target input is a JSFunction, since it can essentially be any
JSReceiver that is a constructor, i.e. it can also be a JSBoundFunction.

Bug: chromium:801627
Change-Id: Ia37bf9c0a751e4665e1167a3771fbe166473c979
Reviewed-on: https://chromium-review.googlesource.com/866493Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50563}