Adds `DartOptions` to generic method syntax tests.

tests/language/generic_methods_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
 
 /// Dart test verifying that the parser can handle type parameterization of
 /// method declarations and method invocations. Slightly adjusted version of
 /// code from DEP #22.
 
 library generic_methods_test;
 
 import "package:expect/expect.dart";
 
 class BinaryTreeNode<K extends Comparable<K>, V> {
@@ skipping 86 matching lines @@
 
   sT = sT.insert(0, "");
   sT = sT.insert(1, " ");
   sT = sT.insert(2, "  ");
   sT = sT.insert(3, "   ");
 
   BinaryTree<num, num> iT = sT.map<num>((String s) => s.length);
 
   Expect.equals(iT.foldPre<num>(0, (int i, num s) => i + s), 6);
 }