Update charted to 0.4.8 and roll

packages/charted/examples/layout/treemap_demo.dart

 /*
  * Copyright 2015 Google Inc. All rights reserved.
  *
  * Use of this source code is governed by a BSD-style
  * license that can be found in the LICENSE file or at
  * https://developers.google.com/open-source/licenses/bsd
  */
 
 library charted.demo.treemap;
 
@@ skipping 41 matching lines @@
     var treemap = root.select(host);
     var div = treemap.append('div')
       ..style('position', 'relative')
       ..style('width', '${width}px')
       ..style('height', '${height}px');
 
     var node = div.selectAll(".node").data(nodes);
     node.enter.append("div")
       ..styleWithCallback('left', (d, i, e) => '${d.x}px')
       ..styleWithCallback('top', (d, i, e) => '${d.y}px')
-      ..styleWithCallback('width', (d, i, e) => '${max(0, d.dx - 1)}px')
-      ..styleWithCallback('height', (d, i, e) => '${max(0, d.dy - 1)}px')
+      ..styleWithCallback('width', (d, i, e) => '${max(0, (d.dx as int) - 1)}px')
+      ..styleWithCallback('height', (d, i, e) => '${max(0, (d.dy as int) - 1)}px')
       ..styleWithCallback('background', (d, i, e) => d.children.isNotEmpty ?
           theme.getColorForKey(d.label, ChartTheme.STATE_NORMAL) : null)
       ..textWithCallback((d, i, e) => d.children.isNotEmpty ? null : d.label)
       ..classed('node');
 
    }
   _createTreeMap('.squarify', TreeMapLayout.TREEMAP_LAYOUT_SQUARIFY);
   _createTreeMap('.slice', TreeMapLayout.TREEMAP_LAYOUT_SLICE);
   _createTreeMap('.dice', TreeMapLayout.TREEMAP_LAYOUT_DICE);
   _createTreeMap('.slicedice', TreeMapLayout.TREEMAP_LAYOUT_SLICE_DICE);
 }