[es6] Array.prototype.find and findIndex should include holes

test/mjsunit/harmony/array-find.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 183 matching lines @@
 
   a = [1, 2, 3];
   found = a.find(function(val, key) { a[key] = ++val; return false; });
   assertArrayEquals([2, 3, 4], a);
   assertEquals(3, a.length);
   assertEquals(undefined, found);
 })();
 
 
 //
-// Test predicate is only called for existing elements
+// Test predicate is called for holes
 //
 (function() {
   var a = new Array(30);
   a[11] = 21;
   a[7] = 10;
   a[29] = 31;
 
   var count = 0;
   a.find(function() { count++; return false; });
-  assertEquals(3, count);
+  assertEquals(30, count);
 })();
 
 
+(function() {
+  var a = [0, 1, , 3];
+  var count = 0;
+  var found = a.find(function(val) { return val === undefined; });
+  assertEquals(undefined, found);
+})();
+
+
+(function() {
+  var a = [0, 1, , 3];
+  a.__proto__ = {
+    __proto__: Array.prototype,
+    2: 42,
+  };
+  var count = 0;
+  var found = a.find(function(val) { return val === 42; });
+  assertEquals(42, found);
+})();
+
+
 //
 // Test thisArg
 //
 (function() {
   // Test String as a thisArg
   var found = [1, 2, 3].find(function(val, key) {
     return this.charAt(Number(key)) === String(val);
   }, "321");
   assertEquals(2, found);
 
@@ skipping 61 matching lines @@
 
 assertThrows('Array.prototype.find.apply({}, null, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, undefined, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, 0, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, true, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, false, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, "", [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, {}, [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, [], [])', TypeError);
 assertThrows('Array.prototype.find.apply({}, /\d+/, [])', TypeError);