Implement DefineOwnProperty for TypedArrays

test/mjsunit/element-accessor.js

 // Copyright 2015 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 () {
   var o = [];
   o.__proto__ = {};
 
@@ skipping 11 matching lines @@
   Object.defineProperty(o, "3", {
     get:function() { return 100; },
     set:function(v) { set = v; }});
 
   store(o, 3, 1000);
   assertEquals(1000, set);
   assertEquals(100, o[3]);
 })();
 
 (function () {
-  var o = new Int32Array();
-  Object.defineProperty(o, "0", {get: function(){}});
-  assertEquals(undefined, Object.getOwnPropertyDescriptor(o, "0"));
+  var o = new Int32Array(1);
+  assertThrows(
+      () => Object.defineProperty(o, '0', {get: function() {}}), TypeError);

[Dan Ehrenberg, 2016/11/28 23:01:40]

Looks like this case started to throw when it previously didn't.

[caitp, 2016/11/28 23:10:10]

Defining accessors on typed arrays used to fail silently, but this was not spec
behaviour. all other impls ive tried match the spec here.

[Dan Ehrenberg, 2016/11/28 23:13:13]

OK, if we're not the first to ship this fix, I'm fine without the UseCounter.

+  assertEquals({
+    value: 0,
+    writable: true,
+    enumerable: true,
+    configurable: false
+  }, Object.getOwnPropertyDescriptor(o, "0"));
 })();
 
 (function() {
   function f() {
     var a = new Array();
     a[1] = 1.5;
     return a;
   }
 
   f();
   f();
   %OptimizeFunctionOnNextCall(f);
   var a = f();
   a[2] = 2;
   assertEquals(3, a.length);
 })();