Remove warning about instantiating an abstract class without implementing a member

tests/language/factory2_test.dart

 // Copyright (c) 2012, 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 default keyword on interfaces
 // Test case for issues 500 and 512
 
 interface Link<T> extends Iterable<T> default LinkFactory<T> {
   // does not match constructor for  LinkFactory
   Link(T head, [Link<T> tail]); /// static type warning
   Link<T> prepend(T element);
 }
 
 interface EmptyLink<T> extends Link<T> default LinkTail<T> {
   const EmptyLink();
 }
 
 class LinkFactory<T> {
   factory Link(head, [Link tail]) {
   }
 }
 
 // Does not implement all of Iterable
-class AbstractLink<T> implements Link<T> {  /// static type warning
+class AbstractLink<T> implements Link<T> {  
   const AbstractLink();
   Link<T> prepend(T element) {
     return new Link<T>(element, this);
   }
 }
 
 // Does not implement all of Iterable
-class LinkTail<T> extends AbstractLink<T>    /// static type warning
+class LinkTail<T> extends AbstractLink<T>   
     implements EmptyLink<T> {
   const LinkTail();
 }
 
 // Does not implement all of Iterable
-class LinkEntry<T> extends AbstractLink<T> {  /// static type warning
+class LinkEntry<T> extends AbstractLink<T> {
   LinkEntry(T head, Link<T> realTail);
 }
 
 class Fisk {
   // instantiation of abstract class
   Link<String> nodes = const EmptyLink();  /// static type warning
 }
 
 main() {
   new Fisk();
   // instantiation of abstract class
   new EmptyLink<String>().prepend('hest'); /// static type warning
   // instantiation of abstract class
   const EmptyLink<String>().prepend('fisk'); /// static type warning
 }