Fix "ignore:" handling with upper case error codes.

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // 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 analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 3151 matching lines @@
    */
   static IgnoreInfo calculateIgnores(String content, LineInfo info) {
     Iterable<Match> matches = _IGNORE_MATCHER.allMatches(content);
     if (matches.isEmpty) {
       return _EMPTY_INFO;
     }
 
     IgnoreInfo ignoreInfo = new IgnoreInfo();
     for (Match match in matches) {
       // See _IGNORE_MATCHER for format --- note the possibility of error lists.
-      Iterable<String> codes =
-          match.group(1).split(',').map((String code) => code.trim());
+      Iterable<String> codes = match
+          .group(1)
+          .split(',')
+          .map((String code) => code.trim().toLowerCase());
       ignoreInfo.addAll(info.getLocation(match.start).lineNumber, codes);
     }
     return ignoreInfo;
   }
 }
 
 /**
  * A task that ensures that all of the inferable instance members in a
  * compilation unit have had their type inferred.
  */
@@ skipping 2951 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }