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/interpreter/unstarted_runtime_test.cc b/runtime/interpreter/unstarted_runtime_test.cc
index 31be587..16b7b55 100644
--- a/runtime/interpreter/unstarted_runtime_test.cc
+++ b/runtime/interpreter/unstarted_runtime_test.cc
@@ -960,7 +960,7 @@
         class_linker->FindClass(self,
                                 "Lsun/misc/FloatingDecimal;",
                                 ScopedNullHandle<mirror::ClassLoader>()));
-    ASSERT_TRUE(floating_decimal.Get() != nullptr);
+    ASSERT_TRUE(floating_decimal != nullptr);
     ASSERT_TRUE(class_linker->EnsureInitialized(self, floating_decimal, true, true));
 
     ArtMethod* caller_method = floating_decimal->FindDeclaredDirectMethod(
@@ -1014,7 +1014,7 @@
           class_linker->FindClass(self,
                                   "Ljava/lang/Double;",
                                   ScopedNullHandle<mirror::ClassLoader>()));
-  ASSERT_TRUE(double_class.Get() != nullptr);
+  ASSERT_TRUE(double_class != nullptr);
   ASSERT_TRUE(class_linker->EnsureInitialized(self, double_class, true, true));
 
   ArtMethod* method = double_class->FindDeclaredDirectMethod("toString",