Add List.asMap().

sdk/lib/collection/collections.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.
 
 part of dart.collection;
 
 /**
  * This class provides default implementations for Iterables (including Lists).
  *
  * Once Dart receives Mixins it will be replaced with mixin classes.
@@ skipping 366 matching lines @@
     if (from is! List) throw new ArgumentError(from);
     if (startFrom is! int) throw new ArgumentError(startFrom);
     if (length < 0) throw new ArgumentError(length);
     if (start < 0) throw new RangeError.value(start);
     if (start + length > list.length) {
       throw new RangeError.value(start + length);
     }
 
     Arrays.copy(from, startFrom, list, start, length);
   }
+
+  static Map<int, dynamic> asMapList(List l) {
+    return new ListMapView(l);
+  }
 }
 
 class Collections {
   static String collectionToString(Collection c)
       => ToString.collectionToString(c);
 }
 
 /**
  * An unmodifiable [List] view of another List.
  *
  * The source of the elements may be a [List] or any [Iterable] with
  * efficient [Iterable.length] and [Iterable.elementAt].
  */
 class UnmodifiableListView<E> extends UnmodifiableListBase<E> {
   Iterable<E> _source;
   /** Create an unmodifiable list backed by [source]. */
   UnmodifiableListView(Iterable<E> source) : _source = source;
   int get length => _source.length;
   E operator[](int index) => _source.elementAt(index);
 }