- Remove arguments definition test from the VM.

tests/corelib/list_fill_range_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 import "dart:collection";
 
 test(List list, int start, int end, [fillValue]) {
   List copy = list.toList();
-  if (?fillValue) {
-    list.fillRange(start, end, fillValue);
-  } else {
-    list.fillRange(start, end, fillValue);
-  }
+  list.fillRange(start, end, fillValue);
   Expect.equals(copy.length, list.length);
   for (int i = 0; i < start; i++) {
     Expect.equals(copy[i], list[i]);
   }
   for (int i = start; i < end; i++) {
     Expect.equals(fillValue, list[i]);
   }
   for (int i = end; i < list.length; i++) {
     Expect.equals(copy[i], list[i]);
   }
@@ skipping 44 matching lines @@
   expectUE(() => test(const [1, 2, 3], 1, 4));
 }
 
 void expectRE(Function f) {
   Expect.throws(f, (e) => e is RangeError);
 }
 
 void expectUE(Function f) {
   Expect.throws(f, (e) => e is UnsupportedError);
 }