Add tests for Number.{MAX,MIN}_SAFE_INTEGER

test/built-ins/Number/MAX_SAFE_INTEGER.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Property descriptor for `Number.MAX_SAFE_INTEGER`
+esid: sec-number.max_safe_integer
+es6id: 20.1.2.6
+info: >
+    The value of Number.MAX_SAFE_INTEGER is 9007199254740991
+
+    This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+    false, [[Configurable]]: false }.
+includes: [propertyHelper.js]
+---*/
+
+var desc = Object.getOwnPropertyDescriptor(Number, 'MAX_SAFE_INTEGER');
+
+assert.sameValue(desc.set, undefined, 'Does not define a `get` accessor');
+assert.sameValue(desc.get, undefined, 'Does not define a `set` accessor');
+assert.sameValue(desc.value, 9007199254740991);
+
+verifyNotEnumerable(Number, 'MAX_SAFE_INTEGER');
+verifyNotWritable(Number, 'MAX_SAFE_INTEGER');
+verifyNotConfigurable(Number, 'MAX_SAFE_INTEGER');

test/built-ins/Number/MIN_SAFE_INTEGER.js

+// Copyright (C) 2016 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Property descriptor for `Number.MIN_SAFE_INTEGER`
+esid: sec-number.min_safe_integer
+es6id: 20.1.2.8
+info: >
+    The value of Number.MIN_SAFE_INTEGER is −9007199254740991
+
+    This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+    false, [[Configurable]]: false }.
+includes: [propertyHelper.js]
+---*/
+
+var desc = Object.getOwnPropertyDescriptor(Number, 'MIN_SAFE_INTEGER');
+
+assert.sameValue(desc.set, undefined, 'Does not define a `get` accessor');
+assert.sameValue(desc.get, undefined, 'Does not define a `set` accessor');
+assert.sameValue(desc.value, -9007199254740991);
+
+verifyNotEnumerable(Number, 'MIN_SAFE_INTEGER');
+verifyNotWritable(Number, 'MIN_SAFE_INTEGER');
+verifyNotConfigurable(Number, 'MIN_SAFE_INTEGER');