ObjPtr<>-ify StackTraceElement and ClassLoader.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I457eeda55bbfb905dd2de0abd68451ab42ef9c1f
diff --git a/runtime/class_loader_context.cc b/runtime/class_loader_context.cc
index 66d134e..428bf30 100644
--- a/runtime/class_loader_context.cc
+++ b/runtime/class_loader_context.cc
@@ -31,6 +31,7 @@
 #include "dex/dex_file_loader.h"
 #include "handle_scope-inl.h"
 #include "jni/jni_internal.h"
+#include "mirror/class_loader-inl.h"
 #include "mirror/object_array-alloc-inl.h"
 #include "nativehelper/scoped_local_ref.h"
 #include "oat_file_assistant.h"