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/native/java_lang_reflect_Method.cc b/runtime/native/java_lang_reflect_Method.cc
index 52e0494..34455fe 100644
--- a/runtime/native/java_lang_reflect_Method.cc
+++ b/runtime/native/java_lang_reflect_Method.cc
@@ -22,6 +22,7 @@
 #include "base/enums.h"
 #include "class_linker-inl.h"
 #include "class_linker.h"
+#include "class_root.h"
 #include "dex/dex_file_annotations.h"
 #include "jni/jni_internal.h"
 #include "mirror/class-inl.h"
@@ -66,12 +67,8 @@
         annotations::GetExceptionTypesForMethod(method);
     if (result_array == nullptr) {
       // Return an empty array instead of a null pointer
-      ObjPtr<mirror::Class> class_class = mirror::Class::GetJavaLangClass();
-      ObjPtr<mirror::Class> class_array_class =
-          Runtime::Current()->GetClassLinker()->FindArrayClass(soa.Self(), &class_class);
-      if (class_array_class == nullptr) {
-        return nullptr;
-      }
+      ObjPtr<mirror::Class> class_array_class = GetClassRoot<mirror::ObjectArray<mirror::Class>>();
+      DCHECK(class_array_class != nullptr);
       mirror::ObjectArray<mirror::Class>* empty_array =
           mirror::ObjectArray<mirror::Class>::Alloc(soa.Self(), class_array_class, 0);
       return soa.AddLocalReference<jobjectArray>(empty_array);