Rename ObjPtr::Decode to ObjPtr::Ptr

Done to prevent ambiguity with ScopedObjectAccess::Decode.

Bug: 31113334

Test: test-art-host
Change-Id: I07a2497cc9cf66386311798933547471987fc316
diff --git a/compiler/optimizing/reference_type_propagation.cc b/compiler/optimizing/reference_type_propagation.cc
index 15cebfe..45a3ce4 100644
--- a/compiler/optimizing/reference_type_propagation.cc
+++ b/compiler/optimizing/reference_type_propagation.cc
@@ -454,7 +454,7 @@
     }
     instr->SetReferenceTypeInfo(
         ReferenceTypeInfo::Create(handle_cache_->GetStringClassHandle(), /* is_exact */ true));
-  } else if (IsAdmissible(klass.Decode())) {
+  } else if (IsAdmissible(klass.Ptr())) {
     ReferenceTypeInfo::TypeHandle handle = handle_cache_->NewHandle(klass);
     is_exact = is_exact || handle->CannotBeAssignedFromOtherTypes();
     instr->SetReferenceTypeInfo(ReferenceTypeInfo::Create(handle, is_exact));