Implement type checking of list literals (issue 220).

runtime/lib/literal_map_factory.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.
-// Immutable map class for compiler generated map literals.
-
-class _LiteralMapFactory {
-  // [elements] contains n key-value pairs. The keys are at position
-  // 2*n, the values at position 2*n+1.
-  factory Map<K, V>.fromLiteral(int location,
-                                String value_type,
-                                List elements) {
-    var map = new LinkedHashMap<String, V>();
-    var len = elements.length;
-    for (int i = 1; i < len; i += 2) {
-      // The type of the key has been checked in the parser already.
-      if (elements[i] is !V) {
-        TypeError._throwNew(location,
-                            elements[i],
-                            value_type,
-                            "map literal value at index ${i ~/ 2}");
-      }
-      map[elements[i-1]] = elements[i];
-    }
-    return map;
-  }
-}