[api] Default native data property setter to replace the setter if the property is writable.

test/mjsunit/regress/regress-crbug-580584.js

Index: test/mjsunit/regress/regress-crbug-580584.js
diff --git a/test/mjsunit/regress/regress-crbug-580584.js b/test/mjsunit/regress/regress-crbug-580584.js
new file mode 100644
index 0000000000000000000000000000000000000000..cb6776f54c8445bd8466726328d19b966ddb55b5
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-580584.js
@@ -0,0 +1,19 @@
+// 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.
+
+function f() { return arguments }
+
+// Reconfiguring function.name should update both the attributes and the value.
+Object.defineProperty(f, "name", {
+  writable: true, configurable: true, value: 10});
+assertEquals({value: 10, writable: true, enumerable: false, configurable: true},
+             Object.getOwnPropertyDescriptor(f, "name"));
+
+var args = f();
+
+// Setting a value for arguments[Symbol.iterator] should not affect the
+// attributes.
+args[Symbol.iterator] = 10;
+assertEquals({value: 10, writable: true, configurable: true, enumerable: false},
+             Object.getOwnPropertyDescriptor(args, Symbol.iterator));