Add tests for InstanceOf's and CheckCast's MustDoNullCheck

Change-Id: I6a2b9293d91d27193625f5c61b0b64733a0c0d82
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 424a393..7da4f2d 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -270,6 +270,16 @@
         << load_cass->MustGenerateClinitCheck() << std::noboolalpha;
   }
 
+  void VisitCheckCast(HCheckCast* check_cast) OVERRIDE {
+    StartAttributeStream("must_do_null_check") << std::boolalpha
+        << check_cast->MustDoNullCheck() << std::noboolalpha;
+  }
+
+  void VisitInstanceOf(HInstanceOf* instance_of) OVERRIDE {
+    StartAttributeStream("must_do_null_check") << std::boolalpha
+        << instance_of->MustDoNullCheck() << std::noboolalpha;
+  }
+
   bool IsPass(const char* name) {
     return strcmp(pass_name_, name) == 0;
   }