[turbofan] Reduce CallConstructWithSpread where iteration is not observable.

test/mjsunit/es6/super-with-spread-modify-array-iterator.js

Index: test/mjsunit/es6/super-with-spread-modify-array-iterator.js
diff --git a/test/mjsunit/es6/super-with-spread-modify-array-iterator.js b/test/mjsunit/es6/super-with-spread-modify-array-iterator.js
new file mode 100644
index 0000000000000000000000000000000000000000..70ce9ca15915e8d2683f3a7d0c7448cafc210707
--- /dev/null
+++ b/test/mjsunit/es6/super-with-spread-modify-array-iterator.js
@@ -0,0 +1,51 @@
+// 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 modifyArrayIterator() {
+  'use strict';
+
+  class Point {
+    constructor(x, y) {
+      this.x = x;
+      this.y = y;
+    }
+  }
+
+  class RestPoint extends Point {
+    constructor(...args) {
+      super(...args);
+    }
+  }
+
+  function testRestPoint(x, y) {
+    return new RestPoint(x, y);
+  }
+  testRestPoint(1, 2);
+  testRestPoint(1, 2);
+  % OptimizeFunctionOnNextCall(testRestPoint);
+  var r = testRestPoint(1, 2);
+
+  assertInstanceof(r, RestPoint);
+  assertInstanceof(r, Point);
+  assertEquals(1, r.x);
+  assertEquals(2, r.y);
+
+  Object.defineProperty(Array.prototype, Symbol.iterator, {
+    value: function*
+        () {
+          yield 3;
+          yield 4;
+        },
+    configurable: true
+  });
+
+  var r2 = testRestPoint(1, 2);
+
+  assertInstanceof(r2, RestPoint);
+  assertInstanceof(r2, Point);
+  assertEquals(3, r2.x);
+  assertEquals(4, r2.y);
+})();