Update charted to 0.4.8 and roll

packages/quiver/lib/check.dart

 // Copyright 2014 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 40 matching lines @@
 int checkListIndex(int index, int size, {message}) {
   if (index < 0 || index >= size) {
     throw new RangeError(_resolveMessage(
         message, 'index $index not valid for list of size $size'));
   }
   return index;
 }
 
 /// Throws an [ArgumentError] if the given [reference] is `null`. Otherwise,
 /// returns the [reference] parameter.
-dynamic checkNotNull(reference, {message}) {
+T checkNotNull<T>(T reference, {message}) {
   if (reference == null) {
     throw new ArgumentError(_resolveMessage(message, 'null pointer'));
   }
   return reference;
 }
 
 /// Throws a [StateError] if the given [expression] is `false`.
 void checkState(bool expression, {message}) {
   if (!expression) {
     throw new StateError(_resolveMessage(message, 'failed precondition'));
   }
 }
 
 String _resolveMessage(message, String defaultMessage) {
   if (message is Function) message = message();
   if (message == null) return defaultMessage;
   return message.toString();
 }