Propagate the read barrier option to Class::VisitNativeRoots.

Propagate the read barrier option from Object::VisitReferences to
Class::VisitNativeRoots.

This is a step toward the GC thread avoiding graying objects (and
reducing dirty pages) in the immune spaces.

Bug: 12687968

Change-Id: I29c4126a4ad4c40e63a934e62451fb3fb36aad43
diff --git a/runtime/art_field.h b/runtime/art_field.h
index b64b70f..aaccbf3 100644
--- a/runtime/art_field.h
+++ b/runtime/art_field.h
@@ -41,6 +41,7 @@
  public:
   ArtField();
 
+  template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
   mirror::Class* GetDeclaringClass() SHARED_REQUIRES(Locks::mutator_lock_);
 
   void SetDeclaringClass(mirror::Class *new_declaring_class)