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/native/java_lang_Class.cc b/runtime/native/java_lang_Class.cc
index 7563161..ceb37c4 100644
--- a/runtime/native/java_lang_Class.cc
+++ b/runtime/native/java_lang_Class.cc
@@ -354,8 +354,8 @@
   ObjPtr<mirror::Constructor> result =
       mirror::Class::GetDeclaredConstructorInternal<kRuntimePointerSize, false>(
       soa.Self(),
-      DecodeClass(soa, javaThis).Ptr(),
-      soa.Decode<mirror::ObjectArray<mirror::Class>>(args).Ptr());
+      DecodeClass(soa, javaThis),
+      soa.Decode<mirror::ObjectArray<mirror::Class>>(args));
   return soa.AddLocalReference<jobject>(result);
 }