Improve Hydrogen code for accessing undefined/null/Infinity.

src/factory.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1297 matching lines @@
   if (!instance_template->IsUndefined()) {
     Execution::ConfigureInstance(instance,
                                  instance_template,
                                  pending_exception);
   } else {
     *pending_exception = false;
   }
 }
 
 
+Handle<Object> Factory::GlobalConstantFor(Handle<String> name) {
+  Heap* h = isolate()->heap();
+  if (name->Equals(h->undefined_symbol())) return undefined_value();
+  if (name->Equals(h->nan_symbol())) return nan_value();
+  if (name->Equals(h->infinity_symbol())) return infinity_value();
+  return Handle<Object>::null();
+}
+
+
 } }  // namespace v8::internal