[es6] implement spread calls

src/harmony-spread.js

Index: src/harmony-spread.js
diff --git a/src/harmony-spread.js b/src/harmony-spread.js
new file mode 100644
index 0000000000000000000000000000000000000000..48972fad08ec48ed37bef4b8a04d56916da56a55
--- /dev/null
+++ b/src/harmony-spread.js
@@ -0,0 +1,33 @@
+// 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.
+
+'use strict';
+
+function SpreadArguments() {
+  var count = %_ArgumentsLength();
+  var args = new InternalArray();
+
+  for (var i = 0; i < count; ++i) {
+    var array = %_Arguments(i);
+    var length = array.length;
+    for (var j = 0; j < length; ++j) {
+      args.push(array[j]);
+    }
+  }
+
+  return args;
+}
+
+
+function SpreadIterable(collection) {
+  if (IS_NULL_OR_UNDEFINED(collection)) {
+    throw MakeTypeError("not_iterable", [collection]);
+  }
+
+  var args = new InternalArray();
+  for (var value of collection) {
+    args.push(value);
+  }
+  return args;
+}