ObjPtr<>-ify ClassLinker::FindClass(), fix 1 stale reference use.

Thread::CreateAnnotatedStackTrace() was using a stale
reference `aste_array_class`.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I191907c0053456bb57de425aa6ccd9668df818a2
diff --git a/runtime/method_handles_test.cc b/runtime/method_handles_test.cc
index a947342..0db9551 100644
--- a/runtime/method_handles_test.cc
+++ b/runtime/method_handles_test.cc
@@ -17,6 +17,7 @@
 #include "method_handles.h"
 
 #include "class_linker-inl.h"
+#include "class_root.h"
 #include "common_runtime_test.h"
 #include "handle_scope-inl.h"
 #include "jvalue-inl.h"
@@ -49,12 +50,11 @@
         REQUIRES_SHARED(Locks::mutator_lock_) {
     ClassLinker* cl = Runtime::Current()->GetClassLinker();
     StackHandleScope<2> hs(self);
-    ObjPtr<mirror::Class> class_type = mirror::Class::GetJavaLangClass();
-    ObjPtr<mirror::Class> class_array_type = cl->FindArrayClass(self, &class_type);
+    ObjPtr<mirror::Class> class_array_type = GetClassRoot<mirror::ObjectArray<mirror::Class>>(cl);
     auto parameter_types = hs.NewHandle(
         mirror::ObjectArray<mirror::Class>::Alloc(self, class_array_type, 1));
     parameter_types->Set(0, parameter_type.Get());
-    Handle<mirror::Class> void_class = hs.NewHandle(cl->FindPrimitiveClass('V'));
+    Handle<mirror::Class> void_class = hs.NewHandle(GetClassRoot(ClassRoot::kPrimitiveVoid, cl));
     return mirror::MethodType::Create(self, void_class, parameter_types);
   }