Move mirror::ObjectArray to ObjPtr

Also reduce calls to ObjPtr::Ptr.

Bug: 31113334

Test: test-art-host -j32

Change-Id: I73e1b356972bb079b66332f00f7f07451601044e
diff --git a/runtime/mirror/object_reference-inl.h b/runtime/mirror/object_reference-inl.h
index 60955d6..e70b936 100644
--- a/runtime/mirror/object_reference-inl.h
+++ b/runtime/mirror/object_reference-inl.h
@@ -24,7 +24,11 @@
 namespace art {
 namespace mirror {
 
-// References between objects within the managed heap.
+template<bool kPoisonReferences, class MirrorType>
+void ObjectReference<kPoisonReferences, MirrorType>::Assign(ObjPtr<MirrorType> ptr) {
+  Assign(ptr.Ptr());
+}
+
 template<class MirrorType>
 HeapReference<MirrorType> HeapReference<MirrorType>::FromObjPtr(ObjPtr<MirrorType> ptr) {
   return HeapReference<MirrorType>(ptr.Ptr());