Change new List(n) to return fixed length list.

samples/swarm/swarm_ui_lib/layout/GridLayout.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.
 
 part of layout;
 
 /**
  * Implements a grid-based layout system based on:
  * [http://dev.w3.org/csswg/css3-grid-align/]
  *
@@ skipping 488 matching lines @@
       span = childLayout.columnSpan;
       tracks = _columnTracks;
     } else if (_dimension == Dimension.HEIGHT) {
       start = childLayout.row - 1;
       span = childLayout.rowSpan;
       tracks = _rowTracks;
     }
 
     assert(start >= 0 && span >= 1);
 
-    final result = new List<GridTrack>.fixedLength(span);
+    final result = new List<GridTrack>(span);
     for (int i = 0; i < span; i++) {
       result[i] = tracks[start + i];
     }
     return result;
   }
 
   int _getSpanCount(ViewLayout item) {
     GridLayoutParams childLayout = item.layoutParams;
     return (_dimension == Dimension.WIDTH ?
         childLayout.columnSpan : childLayout.rowSpan);
   }
 }