[destructuring] Implement spread binding patterns.

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 --harmony-computed-property-names
 
 (function TestObjectLiteralPattern() {
   var { x : x, y : y } = { x : 1, y : 2 };
   assertEquals(1, x);
   assertEquals(2, y);
@@ skipping 445 matching lines @@
 
   (function() {
     log = [];
     // last comma is not an elision, but the comma before the last is.
     var [a, b, ,] = f();
     assertSame(1, a);
     assertSame(2, b);
     assertArrayEquals(["1", "2", "3"], log);
   }());
 
+  (function() {
+    log = [];
+    var [a, ...rest] = f();
+    assertSame(1, a);
+    assertArrayEquals([2,3], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
+
+  (function() {
+    log = [];
+    var [a, b, c, ...rest] = f();
+    assertSame(1, a);
+    assertSame(2, b);
+    assertSame(3, c);
+    assertArrayEquals([], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
+
+  (function() {
+    log = [];
+    var [a, b, c, d, ...rest] = f();
+    assertSame(1, a);
+    assertSame(2, b);
+    assertSame(3, c);
+    assertSame(undefined, d);
+    assertArrayEquals([], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
 }());
 
 
 (function TestIteratorsLexical() {
   'use strict';
   var log = [];
   function* f() {
     log.push("1");
     yield 1;
     log.push("2");
@@ skipping 50 matching lines @@
 
   (function() {
     log = [];
     // last comma is not an elision, but the comma before the last is.
     let [a, b, ,] = f();
     assertSame(1, a);
     assertSame(2, b);
     assertArrayEquals(["1", "2", "3"], log);
   }());
 
+  (function() {
+    log = [];
+    let [a, ...rest] = f();
+    assertSame(1, a);
+    assertArrayEquals([2,3], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
+
+  (function() {
+    log = [];
+    let [a, b, c, ...rest] = f();
+    assertSame(1, a);
+    assertSame(2, b);
+    assertSame(3, c);
+    assertArrayEquals([], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
+
+  (function() {
+    log = [];
+    let [a, b, c, d, ...rest] = f();
+    assertSame(1, a);
+    assertSame(2, b);
+    assertSame(3, c);
+    assertSame(undefined, d);
+    assertArrayEquals([], rest);
+    assertArrayEquals(["1", "2", "3", "done"], log);
+  }());
 }());
 
 (function TestIteratorsRecursive() {
-
   var log = [];
   function* f() {
     log.push("1");
     yield {x : 1, y : 2};
     log.push("2");
     yield [42, 27, 30];
     log.push("3");
     yield "abc";
     log.push("done");
   };
@@ skipping 11 matching lines @@
     'use strict';
     log = [];
     let [{x, y}, [a, b]] = f();
     assertSame(1, x);
     assertSame(2, y);
     assertSame(42, a);
     assertSame(27, b);
     assertArrayEquals(["1", "2"], log);
   }());
 }());