Support rest element pattern with user-defined iterable

test/mjsunit/harmony/destructuring.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: --harmony-destructuring-bind
 // Flags: --harmony-default-parameters
 
 (function TestObjectLiteralPattern() {
   var { x : x, y : y, get, set } = { x : 1, y : 2, get: 3, set: 4 };
   assertEquals(1, x);
@@ skipping 485 matching lines @@
     assertSame(1, a);
     assertSame(2, b);
     assertSame(3, c);
     assertSame(undefined, d);
     assertArrayEquals([], rest);
     assertArrayEquals(["1", "2", "3", "done"], log);
   }());
 }());
 
 
+(function TestRestCustomIterable() {
+    var idx = 0;
+    var iterable = {};
+    var iterator = {
+      next: function() {
+        idx += 1;
+        return {
+          value: idx,
+          done: idx === 4
+        };
+      }
+    };
+    iterable[Symbol.iterator] = function() {
+      return iterator;
+    };
+
+    var [...result] = iterable;
+
+    assertEquals([1, 2, 3], result);
+}());
+
+
 (function TestIteratorsLexical() {
   'use strict';
   var log = [];
   function* f() {
     log.push("1");
     yield 1;
     log.push("2");
     yield 2;
     log.push("3");
     yield 3;
@@ skipping 609 matching lines @@
     throw [1, 2, 3];
   } catch ([foo, ...bar]) {
     assertEquals(1, foo);
     assertEquals([2, 3], bar);
   }
 
   assertEquals("hello", foo);
   assertEquals("world", bar);
   assertEquals(42, baz);
 })();