ART: Add operator == and != with nullptr to Handle

Get it in line with ObjPtr and prettify our code.

Test: m
Change-Id: I1322e2a9bc7a85d7f2441034a19bf4d807b81a0e
diff --git a/runtime/entrypoints/quick/quick_field_entrypoints.cc b/runtime/entrypoints/quick/quick_field_entrypoints.cc
index 4544aef..822c5a8 100644
--- a/runtime/entrypoints/quick/quick_field_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_field_entrypoints.cc
@@ -48,7 +48,7 @@
   StackHandleScope<1> hs(self);
   HandleWrapper<mirror::Object> h(hs.NewHandleWrapper(obj));
   ArtField* field = FindFieldFromCode<type, kAccessCheck>(field_idx, referrer, self, size);
-  if (LIKELY(field != nullptr) && UNLIKELY(h.Get() == nullptr)) {
+  if (LIKELY(field != nullptr) && UNLIKELY(h == nullptr)) {
     ThrowNullPointerExceptionForFieldAccess(field, /*is_read*/FindFieldTypeIsRead(type));
     return nullptr;
   }