Update charted to 0.4.8 and roll

packages/charted/lib/svg/axis.dart

 //
 // Copyright 2014 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.svg.axis;
 
@@ skipping 81 matching lines @@
         ellipsized = axisTicksBuilder.shortenedTicks;
 
     var ticks = group.selectAll('.tick').data(values, current.scale),
         exit = ticks.exit,
         transform = isVertical ? _yAxisTransform : _xAxisTransform,
         sign = isTop || isLeft ? -1 : 1,
         isEllipsized = ellipsized != formatted;
 
     var enter = ticks.enter.appendWithCallback((d, i, e) {
       var group = Namespace.createChildElement('g', e)
-        ..attributes['class'] = 'tick'
         ..append(Namespace.createChildElement('line', e))
         ..append(Namespace.createChildElement('text', e)
           ..attributes['dy'] =
               isVertical ? '0.32em' : (isBottom ? '0.71em' : '0'));
       if (!isInitialRender) {
         group.style.setProperty('opacity', EPSILON.toString());
       }
       return group;
     });
 
     // All attributes/styles/classes that may change due to theme and scale.
     // TODO(prsd): Order elements before updating ticks.
     ticks.each((d, i, e) {
+      e.attributes['class'] = 'tick tick-$i';
       Element line = e.firstChild;
       Element text = e.lastChild;
       bool isRTLText = false; // FIXME(prsd)
 
       if (isHorizontal) {
         line.attributes['y2'] = '${sign * innerTickSize}';
         text.attributes['y'] =
             '${sign * (math.max(innerTickSize, 0) + tickPadding)}';
 
         if (axisTicksBuilder.rotation != 0) {
@@ skipping 97 matching lines @@
   /// List of ticks that will be displayed on the axis.
   Iterable get ticks => _ticks;
 
   /// List of formatted ticks values.
   Iterable get formattedTicks => _formattedTicks;
 
   /// List of clipped tick values, if they had to be clipped. Must be same
   /// as the [formattedTicks] if none of the ticks were ellipsized.
   Iterable get shortenedTicks => _formattedTicks;
 }