ObjPtr<>-ify ArtMethod and mirror::Method.

And clean up some forgotten things after old CLs.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I8af0e845c24d674d0efab21d80c29949b1cc0593
diff --git a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index 505e183..9cae3ae 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -2146,7 +2146,7 @@
       sm_.AdvancePointer(self->GetJniEnv());
 
       if (is_static) {
-        sm_.AdvanceHandleScope((**sp)->GetDeclaringClass());
+        sm_.AdvanceHandleScope((**sp)->GetDeclaringClass().Ptr());
       }  // else "this" reference is already handled by QuickArgumentVisitor.
     }
   }