Make Null a public class of dart:core.

runtime/vm/resolver.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/resolver.h"
 
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/symbols.h"
 
 namespace dart {
 
 DEFINE_FLAG(bool, trace_resolving, false, "Trace resolving.");
 
 
 // The actual names of named arguments are not checked by the dynamic resolver,
 // but by the method entry code. It is important that the dynamic resolver
 // checks that no named arguments are passed to a method that does not accept
 // them, since the entry code of such a method does not check for named
 // arguments. The dynamic resolver actually checks that a valid number of named
 // arguments is passed in.
 RawFunction* Resolver::ResolveDynamic(const Instance& receiver,
                                       const String& function_name,
                                       const ArgumentsDescriptor& args_desc) {
   // Figure out type of receiver first.
-  Class& cls = Class::Handle();
-  cls = receiver.clazz();
-  // For lookups treat null as an instance of class Object.
-  if (cls.IsNullClass()) {
-    cls = Isolate::Current()->object_store()->object_class();
-  }
-  ASSERT(!cls.IsNull());
-
+  const Class& cls = Class::Handle(receiver.clazz());
   return ResolveDynamicForReceiverClass(cls, function_name, args_desc);
 }
 
 
 RawFunction* Resolver::ResolveDynamicForReceiverClass(
     const Class& receiver_class,
     const String& function_name,
     const ArgumentsDescriptor& args_desc) {
 
   Function& function =
@@ skipping 209 matching lines @@
       OS::Print("ResolveStatic error '%s': %s.\n",
                 function_name.ToCString(),
                 error_message.ToCString());
     }
     return Function::null();
   }
   return function.raw();
 }
 
 }  // namespace dart