Fix wrong type test optimization when testing against a signature class: we must always consider th…

runtime/lib/object.cc

Index: runtime/lib/object.cc
===================================================================
--- runtime/lib/object.cc	(revision 24952)
+++ runtime/lib/object.cc	(working copy)
@@ -14,6 +14,7 @@
 namespace dart {
 
 DECLARE_FLAG(bool, enable_type_checks);
+DECLARE_FLAG(bool, trace_type_checks);
 
 
 DEFINE_NATIVE_ENTRY(Object_cid, 1) {
@@ -127,6 +128,17 @@
         Symbols::Empty(), malformed_error_message);
     UNREACHABLE();
   }
+
+  if (FLAG_trace_type_checks) {
+    const char* result_str = is_instance_of ? "true" : "false";
+    OS::Print("Object.instanceOf: result %s\n", result_str);
+    const Class& instance_class = Class::Handle(instance.clazz());
+    OS::Print("  instance  [class: %s]\n",
+        String::Handle(instance_class.Name()).ToCString());
+    OS::Print("  test-type [class: %s]\n",
+        String::Handle(Class::Handle(type.type_class()).Name()).ToCString());
+    OS::Print("  type-args %s\n", instantiator_type_arguments.ToCString());
+  }
   return Bool::Get(negate.value() ? !is_instance_of : is_instance_of);
 }