Enable syntax-only support for generic functions by default.

tests/language/generic_methods_type_expression_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.
 //
-// DartOptions=--generic-method-syntax
 // VMOptions=--generic-method-syntax
 
 /// Dart test on the usage of method type arguments in type expressions. With
 /// '--generic-method-syntax', the type argument is available at runtime,
 /// but erased to `dynamic`.
 
 library generic_methods_type_expression_test;
 
 import "package:expect/expect.dart";
 
@@ skipping 42 matching lines @@
   Expect.throws(() => f7<int>(), (e) => e is TypeError);
   Expect.equals(f8<int>(), List); // Returns `List<dynamic>`.
 
   Expect.isTrue(f9<int>(<int,String>{}));
   Expect.isTrue(f9<int>(<bool,String>{})); // `is Map<dynamic, String>` is true.
   Expect.isFalse(f9<int>(<int,int>{}));
 
   Expect.isTrue(new IsMap<int>().check<String>(<int,String>{}));
   Expect.isTrue(new IsMap<int>().check<int>(<int,String>{}));
 }