Support rest parameters in arrow functions

test/mjsunit/harmony/rest-params-lazy-parsing.js

 // Copyright 2014 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-rest-parameters --min-preparse-length=0
+// Flags: --harmony-rest-parameters --harmony-arrow-functions
+// Flags: --min-preparse-length=0
 
 function variadic(co, ...values) {
   var sum = 0;
   while (values.length) {
     sum += co * values.pop();
   }
   return sum;
 }
 
+var arrowVariadic = (co, ...values) => {
+  var sum = 0;
+  while (values.length) {
+    sum += co * values.pop();
+  }
+  return sum;
+}
+
+assertEquals(1, variadic.length);
+assertEquals(1, arrowVariadic.length);
+
 assertEquals(90, variadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9));
 assertEquals(74, variadic(2, 1, 2, 3, 4, 5, 6, 7, 9));
 assertEquals(110, variadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
+
+assertEquals(90, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9));
+assertEquals(74, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 9));
+assertEquals(110, arrowVariadic(2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10));