Improve coverage for Error.prototype.toString

Extend coverage to include the property's enumerability, writability,
and configurability.

test/built-ins/Error/prototype/toString/S15.11.4.4_A1.js

@@ -1,16 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The Error.prototype has toString property
-es5id: 15.11.4.4_A1
-description: Checking Error.prototype.toString
----*/
-
-//////////////////////////////////////////////////////////////////////////////
-// CHECK#1
-if (!Error.prototype.hasOwnProperty('toString')) {
-  throw new Test262Error('#1: Error.prototype.hasOwnProperty(\'toString\') return true. Actual: ' + Error.prototype.hasOwnProperty('toString'));
-}
-//
-//////////////////////////////////////////////////////////////////////////////

test/built-ins/Error/prototype/toString/prop-desc.js

@@ -0,0 +1,13 @@
+// Copyright (c) 2021 the V8 project authors.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-error.prototype.toString
+description: Property descriptor of Error.prototype.toString
+includes: [propertyHelper.js]
+---*/
+
+verifyProperty(Error.prototype, 'toString', {
+  enumerable: false,
+  writable: true,
+  configurable: true,
+});