[crankshaft] Not all HAdd instructions produce a number.

test/mjsunit/regress/regress-crbug-664084.js

Index: test/mjsunit/regress/regress-crbug-664084.js
diff --git a/test/mjsunit/regress/regress-crbug-664084.js b/test/mjsunit/regress/regress-crbug-664084.js
new file mode 100644
index 0000000000000000000000000000000000000000..79e221e4955d1c54ab22c83ff7398139d9685665
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-664084.js
@@ -0,0 +1,14 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function foo() {
+  return +({} + 1);
+}
+
+assertEquals(NaN, foo());
+assertEquals(NaN, foo());
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(NaN, foo());