Implement a native identical function in the VM.

runtime/lib/identical.cc

Index: runtime/lib/identical.cc
diff --git a/runtime/lib/identical.cc b/runtime/lib/identical.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4c452e0299e542fe6a492c8a10aec1c521c14057
--- /dev/null
+++ b/runtime/lib/identical.cc
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+// 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 "vm/bootstrap_natives.h"
+
+#include "vm/object.h"
+
+namespace dart {
+
+DEFINE_NATIVE_ENTRY(Identical_comparison, 2) {
+  GET_NATIVE_ARGUMENT(Instance, a, arguments->NativeArgAt(0));
+  GET_NATIVE_ARGUMENT(Instance, b, arguments->NativeArgAt(1));
+  if (a.raw() == b.raw()) return Bool::True();
+  if (a.IsInteger() && b.IsInteger()) {
+    return Bool::Get(a.Equals(b));
+  }
+  if (a.IsDouble() && b.IsDouble()) {
+    if (a.Equals(b)) return Bool::True();
+    // Check for NaN.
+    const Double& a_double = Double::Cast(a);
+    const Double& b_double = Double::Cast(b);
+    if (isnan(a_double.value()) && isnan(b_double.value())) {
+      return Bool::True();
+    }
+  }
+  return Bool::False();
+}
+
+
+}  // namespace dart