Don't mix commented and uncommented generics.

lib/src/wrappers.dart

 // Copyright (c) 2013, 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.
 
 import "dart:collection";
 import "dart:math" as math;
 
 import "typed_wrappers.dart";
 import "unmodifiable_wrappers.dart";
 
@@ skipping 341 matching lines @@
   /// This soundly converts a [Map] without generic types to a `Map<K, V>` by
   /// asserting that its keys are instances of `E` and its values are instances
   /// of `V` whenever they're accessed. If they're not, it throws a [CastError].
   /// Note that even if an operation throws a [CastError], it may still mutate
   /// the underlying collection.
   ///
   /// This forwards all operations to [base], so any changes in [base] will be
   /// reflected in [this]. If [base] is already a `Map<K, V>`, it's returned
   /// unmodified.
   static Map/*<K, V>*/ typed/*<K, V>*/(Map base) =>
-      base is Map<K, V> ? base : new TypeSafeMap<K, V>(base);
+      base is Map/*<K, V>*/ ? base : new TypeSafeMap/*<K, V>*/(base);
 
   V operator [](Object key) => _base[key];
 
   void operator []=(K key, V value) {
     _base[key] = value;
   }
 
   void addAll(Map<K, V> other) {
     _base.addAll(other);
   }
@@ skipping 224 matching lines @@
 
   /// Returns a new set which contains all the elements of [this] and [other].
   ///
   /// That is, the returned set contains all the elements of this [Set] and all
   /// the elements of [other].
   ///
   /// Note that the returned set will use the default equality operation, which
   /// may be different than the equality operation [this] uses.
   Set<V> union(Set<V> other) => toSet()..addAll(other);
 }