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/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index 727ca7d..8638e34 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -1214,7 +1214,7 @@
   Handle<mirror::ObjectArray<mirror::Object>> roots(
       hs.NewHandle(mirror::ObjectArray<mirror::Object>::Alloc(
           self, class_linker->GetClassRoot(ClassLinker::kObjectArrayClass), number_of_roots)));
-  if (roots.Get() == nullptr) {
+  if (roots == nullptr) {
     // Out of memory, just clear the exception to avoid any Java exception uncaught problems.
     DCHECK(self->IsExceptionPending());
     self->ClearException();