Don't print TODOs in Dart based analyzer.

pkg/analyzer/lib/src/error_formatter.dart

 // Copyright (c) 2013, 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 error_formatter;
 
 import 'generated/engine.dart';
 import 'generated/error.dart';
 import 'generated/source_io.dart';
 import '../options.dart';
 
+/// Returns `true` if [AnalysisError] should be printed.
+typedef bool _ErrorFilter(AnalysisError error);
+
+/// Allows any [AnalysisError].
+bool _anyError(AnalysisError error) => true;
+
 /**
  * Helper for formatting [AnalysisError]s.
  * The two format options are a user consumable format and a machine consumable format.
  */
 class ErrorFormatter {
-  StringSink out;
-  CommandLineOptions options;
+  final StringSink out;
+  final CommandLineOptions options;
+  final _ErrorFilter errorFilter;
 
-  ErrorFormatter(this.out, this.options);
+  ErrorFormatter(this.out, this.options, [this.errorFilter = _anyError]);
 
   void formatErrors(List<AnalysisErrorInfo> errorInfos) {
     var errors = new List<AnalysisError>();
     var errorToLine = new Map<AnalysisError, LineInfo>();
     for (AnalysisErrorInfo errorInfo in errorInfos) {
       for (AnalysisError error in errorInfo.errors) {
-        errors.add(error);
-        errorToLine[error] = errorInfo.lineInfo;
+        if (errorFilter(error)) {
+          errors.add(error);
+          errorToLine[error] = errorInfo.lineInfo;
+        }
       }
     }
     // sort errors
     errors.sort((AnalysisError error1, AnalysisError error2) {
       // severity
       int compare = error2.errorCode.errorSeverity.compareTo(error1.errorCode.errorSeverity);
       if (compare != 0) {
         return compare;
       }
       // path
@@ skipping 116 matching lines @@
   }
 
   static String pluralize(String word, int count) {
     if (count == 1) {
       return word;
     } else {
       return word + "s";
     }
   }
 }