Use Object::null_instance and Object::null_function and do not create Handles everytime.

runtime/vm/object.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 368 matching lines @@
     return *null_array_;
   }
   static const String& null_string() {
     ASSERT(null_string_ != NULL);
     return *null_string_;
   }
   static const Instance& null_instance() {
     ASSERT(null_instance_ != NULL);
     return *null_instance_;
   }
+  static const Function& null_function() {
+    ASSERT(null_function_ != NULL);
+    return *null_function_;
+  }
   static const TypeArguments& null_type_arguments() {
     ASSERT(null_type_arguments_ != NULL);
     return *null_type_arguments_;
   }
 
   static const Array& empty_array() {
     ASSERT(empty_array_ != NULL);
     return *empty_array_;
   }
   static const Array& zero_array() {
@@ skipping 381 matching lines @@
   static RawClass* language_error_class_;  // Class of LanguageError.
   static RawClass* unhandled_exception_class_;  // Class of UnhandledException.
   static RawClass* unwind_error_class_;  // Class of UnwindError.
 
   // The static values below are read-only handle pointers for singleton
   // objects that are shared between the different isolates.
   static Object* null_object_;
   static Array* null_array_;
   static String* null_string_;
   static Instance* null_instance_;
+  static Function* null_function_;
   static TypeArguments* null_type_arguments_;
   static Array* empty_array_;
   static Array* zero_array_;
   static ObjectPool* empty_object_pool_;
   static PcDescriptors* empty_descriptors_;
   static LocalVarDescriptors* empty_var_descriptors_;
   static ExceptionHandlers* empty_exception_handlers_;
   static Array* extractor_parameter_types_;
   static Array* extractor_parameter_names_;
   static Instance* sentinel_;
@@ skipping 7235 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_