Update charted to 0.4.8 and roll

packages/charted/lib/svg/axis.dart

Index: packages/charted/lib/svg/axis.dart
diff --git a/packages/charted/lib/svg/axis.dart b/packages/charted/lib/svg/axis.dart
index 474b4365ba273afe5efeb49ac3155905af297441..fdc7d6083ea2d8efa846ed6bd155ea8c31c0a8ba 100644
--- a/packages/charted/lib/svg/axis.dart
+++ b/packages/charted/lib/svg/axis.dart
@@ -99,7 +99,6 @@ class SvgAxis {
 
     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'] =
@@ -113,6 +112,7 @@ class SvgAxis {
     // 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)