[turbofan] Reduce CallConstructWithSpread where iteration is not observable.

test/mjsunit/es6/super-with-spread-modify-next.js

Index: test/mjsunit/es6/super-with-spread-modify-next.js
diff --git a/test/mjsunit/es6/super-with-spread-modify-next.js b/test/mjsunit/es6/super-with-spread-modify-next.js
new file mode 100644
index 0000000000000000000000000000000000000000..8ae0d6c5898d26a4e6e85df42093aa9410a8d378
--- /dev/null
+++ b/test/mjsunit/es6/super-with-spread-modify-next.js
@@ -0,0 +1,56 @@
+// Copyright 2017 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 modifyNext() {
+  'use strict';
+
+  class Point {
+    constructor(x, y) {
+      this.x = x;
+      this.y = y;
+    }
+  }
+
+  class ArgumentsPoint extends Point {
+    constructor() {
+      super(...arguments);
+    }
+  }
+
+  var a = [];
+  var ai = a[Symbol.iterator]();
+
+  var original_next = ai.__proto__['next'];
+
+  function testArgumentsPoint(x, y) {
+    return new ArgumentsPoint(x, y);
+  }
+  testArgumentsPoint(1, 2);
+  testArgumentsPoint(1, 2);
+  % OptimizeFunctionOnNextCall(testArgumentsPoint);
+  var r = testArgumentsPoint(1, 2);
+
+  assertInstanceof(r, ArgumentsPoint);
+  assertInstanceof(r, Point);
+  assertEquals(r.x, 1);
+  assertEquals(r.y, 2);
+
+  var called = 0;
+  Object.defineProperty(ai.__proto__, 'next', {
+    get: function() {
+      called++;
+      return original_next;
+    }
+  });
+
+  var r2 = testArgumentsPoint(1, 2);
+
+  assertEquals(3, called);
+  assertInstanceof(r2, ArgumentsPoint);
+  assertInstanceof(r2, Point);
+  assertEquals(r2.x, 1);
+  assertEquals(r2.y, 2);
+})();