Make the implementations of InstanceMirror.hashCode use dart:core's identityHashCode.

runtime/lib/mirrors.cc

 // 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.
 
 #include "lib/invocation_mirror.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/object_store.h"
@@ skipping 1046 matching lines @@
                            Instance::null_instance());
 }
 
 
 DEFINE_NATIVE_ENTRY(TypeVariableMirror_upper_bound, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(TypeParameter, param, arguments->NativeArgAt(0));
   return param.bound();
 }
 
 
-DEFINE_NATIVE_ENTRY(InstanceMirror_identityHash, 1) {
-  GET_NATIVE_ARGUMENT(Instance, reflectee, arguments->NativeArgAt(0));
-  ObjectStore* object_store = isolate->object_store();
-  const Class& cls = Class::Handle(isolate, object_store->object_class());
-  const Function& function =
-      Function::Handle(isolate, cls.LookupDynamicFunction(Symbols::hashCode()));
-  const Array& args = Array::Handle(isolate, Array::New(1));
-  args.SetAt(0, reflectee);
-  return DartEntry::InvokeFunction(function, args);
-}
-
-
 DEFINE_NATIVE_ENTRY(InstanceMirror_invoke, 5) {
   // Argument 0 is the mirror, which is unused by the native. It exists
   // because this native is an instance method in order to be polymorphic
   // with its cousins.
   GET_NATIVE_ARGUMENT(Instance, reflectee, arguments->NativeArgAt(1));
   GET_NON_NULL_NATIVE_ARGUMENT(
       String, function_name, arguments->NativeArgAt(2));
   GET_NON_NULL_NATIVE_ARGUMENT(Array, args, arguments->NativeArgAt(3));
   GET_NON_NULL_NATIVE_ARGUMENT(Array, arg_names, arguments->NativeArgAt(4));
 
@@ skipping 606 matching lines @@
 }
 
 
 DEFINE_NATIVE_ENTRY(VariableMirror_type, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(MirrorReference, ref, arguments->NativeArgAt(0));
   const Field& field = Field::Handle(ref.GetFieldReferent());
   return field.type();
 }
 
 }  // namespace dart