Move mirror::ObjectArray to ObjPtr

Also reduce calls to ObjPtr::Ptr.

Bug: 31113334

Test: test-art-host -j32

Change-Id: I73e1b356972bb079b66332f00f7f07451601044e
diff --git a/compiler/driver/compiler_driver-inl.h b/compiler/driver/compiler_driver-inl.h
index d807fca..9711516 100644
--- a/compiler/driver/compiler_driver-inl.h
+++ b/compiler/driver/compiler_driver-inl.h
@@ -98,7 +98,7 @@
   DCHECK(!resolved_field->IsStatic());
   ObjPtr<mirror::Class> fields_class = resolved_field->GetDeclaringClass();
   bool fast_get = referrer_class != nullptr &&
-      referrer_class->CanAccessResolvedField(fields_class.Ptr(),
+      referrer_class->CanAccessResolvedField(fields_class,
                                              resolved_field,
                                              dex_cache,
                                              field_idx);