Update charted to 0.4.8 and roll

packages/yaml/lib/src/parser.dart

Index: packages/yaml/lib/src/parser.dart
diff --git a/packages/yaml/lib/src/parser.dart b/packages/yaml/lib/src/parser.dart
index b44043a1e62f3adf2afd46d9e6c1dc11c8504672..df6ed75f5549655ecc91cb207bea08fe5f1c0060 100644
--- a/packages/yaml/lib/src/parser.dart
+++ b/packages/yaml/lib/src/parser.dart
@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library yaml.parser;
-
 import 'package:source_span/source_span.dart';
 import 'package:string_scanner/string_scanner.dart';
 
@@ -669,7 +667,7 @@ class Parser {
   Pair<VersionDirective, List<TagDirective>> _processDirectives() {
     var token = _scanner.peek();
 
-    var versionDirective;
+    VersionDirective versionDirective;
     var tagDirectives = <TagDirective>[];
     while (token.type == TokenType.VERSION_DIRECTIVE ||
            token.type == TokenType.TAG_DIRECTIVE) {