Update charted to 0.4.8 and roll

packages/dart_to_js_script_rewriter/tool/dev.dart

 library dart_to_js_script_rewriter.tool.dev;
 
 import 'package:dart_dev/dart_dev.dart' show dev, config;
 
 main(List<String> args) async {
   List<String> directories = ['example/', 'lib/', 'test/', 'tool/'];
 
   config.analyze.entryPoints = directories;
+  config.analyze.strong = true;
   config.format.directories = directories;
   config.test
     ..platforms = ['vm']
     ..pubServe = true
     ..unitTests = ['test/unit_test.dart']
     ..integrationTests = ['test/integration_test.dart'];
 
   config.coverage.pubServe = true;
 
   await dev(args);
 }