null is an instance of Dynamic (fix issue 443).

runtime/vm/object.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "vm/assembler.h"
 #include "vm/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
@@ skipping 5020 matching lines @@
 
 
 bool Instance::TestType(TypeTestKind test,
                         const Type& other,
                         const TypeArguments& other_instantiator) const {
   ASSERT(other.IsFinalized());
   ASSERT(!other.IsDynamicType());
   ASSERT(!other.IsVoidType());
   if (IsNull()) {
     if (test == Type::kIsSubtypeOf) {
-      const Type& object_type =
-          Type::Handle(Isolate::Current()->object_store()->object_type());
-      if (other.IsInstantiated() && object_type.IsSubtypeOf(other)) {
-        ASSERT(other_instantiator.IsNull());
-        // null is an instance of the Object class.
-        return true;
+      Class& other_class = Class::Handle();
+      if (other.IsTypeParameter()) {
+        if (other_instantiator.IsNull()) {
+          return true;  // Other type is uninstantiated, i.e. Dynamic.
+        }
+        const Type& instantiated_other =
+            Type::Handle(other_instantiator.TypeAt(other.Index()));
+        ASSERT(instantiated_other.IsInstantiated());
+        other_class = instantiated_other.type_class();
+      } else {
+        other_class = other.type_class();
       }
-      return false;
+      return other_class.IsObjectClass() || other_class.IsDynamicClass();
     } else {
       ASSERT(test == Type::kIsAssignableTo);
       return true;
     }
   }
   const Class& cls = Class::Handle(clazz());
   TypeArguments& type_arguments = TypeArguments::Handle();
   const intptr_t num_type_arguments = cls.NumTypeArguments();
   if (num_type_arguments > 0) {
     type_arguments = GetTypeArguments();
@@ skipping 2208 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart