Update comments in core lib showing proper factory syntax.

corelib/src/set.dart

 // Copyright (c) 2011, 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.
 
 /**
  * This class is the public interface of a set. A set is a collection
  * without duplicates.
  */
-interface Set<E> extends Collection<E> factory HashSetImplementation/* <E> */ {
-// Bug 5408808: Factory should be HashSetImplementation<E>
+interface Set<E> extends Collection<E>
+    factory HashSetImplementation/*<E extends Hashable>*/ {
+// See issue 417. Works in the vm, fails in dartc and frog.
   Set();
 
   /**
    * Creates a [Set] that contains all elements of [other].
    */
   Set.from(Iterable<E> other);
 
   /**
    * Returns true if [value] is in the set.
    */
@@ skipping 41 matching lines @@
   Set<E> intersection(Collection<E> other);
 
   /**
    * Removes all elements in the set.
    */
   void clear();
 
 }
 
 interface HashSet<E extends Hashable> extends Set<E>
-    factory HashSetImplementation /* <E> */ {
-// Bug 5408808: Factory should be HashSetImplementation<E>
+    factory HashSetImplementation/*<E extends Hashable>*/ {
+// See issue 417. Works in the vm, fails in dartc and frog.
   HashSet();
 
   /**
    * Creates a [Set] that contains all elements of [other].
    */
   HashSet.from(Iterable<E> other);
 }