Ensure object ArraySet with null value does not need a type check.

The art::PrepareForRegisterAllocation visitor can remove an
art::BoundType instruction as value input of an
art::ArraySet instruction, possibly replacing it with an
art::NullConstant.  If this happens, remove the need for a
type check in this art::ArraySet.

Bug: 27638110
Change-Id: I6270f8a8e22822a24d8a5919df427ca9c64d121b
6 files changed