Allow VM precompiled to pass trailing-comma test.

tests/language/arg_param_trailing_comma_test.dart

 // Copyright (c) 2016, 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.
 // Dart test program for testing params.
 
 // Convenience values.
 var c = new C();
 var x = 42;
 var y = 42;
 var z = 42;
@@ skipping 57 matching lines @@
   void instancexy(x, [y, ]) {}                        /// none: continued
   void instancez({z, }) {}                            /// none: continued
   void instancexz(x, {z, }) {}                        /// none: continued
 
   void set instancesetx(x, ) {}                       /// none: continued
 
   operator +(x, ) => this;                            /// none: continued
   operator []=(x, y, ) {}                             /// none: continued
 }
 
-main(
-    args,                                             /// main_with_trailing

[Lasse Reichstein Nielsen, 2016/07/05 08:19:09]

It's not an important test, mainly a curiosity, so I think it's safer to just
drop the argument. It's not worth the complication.

-    ) {
+main() {
   testCalls();                                        /// none: continued
   // Make sure the Bad class is checked.
   new Bad().method();
 }
 
 void testCalls() {
   // Check that all functions can be called normally
   topx(x);                                            /// none: continued
   topy(y);                                            /// none: continued
   topxy(x, y);                                        /// none: continued
@@ skipping 303 matching lines @@
 typedef void BadPosMiddle([a,, b]);              /// 201: compile-time error
 typedef void BadNamEmpty({});                    /// 202: compile-time error
 typedef void BadNamEmpty(,{});                   /// 203: compile-time error
 typedef void BadNamEmpty({,});                   /// 204: compile-time error
 typedef void BadNamEmpty({},);                   /// 205: compile-time error
 typedef void BadNamStart(,{a});                  /// 206: compile-time error
 typedef void BadNamStart({, a});                 /// 207: compile-time error
 typedef void BadNamEnd({a,,});                   /// 208: compile-time error
 typedef void BadNamStart({a},);                  /// 209: compile-time error
 typedef void BadNamMiddle({a,, b});              /// 210: compile-time error