Use ansi color in the dartanalyzer cli output.

pkg/analyzer/lib/src/dart/analysis/driver.dart

 // Copyright (c) 2016, 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.
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:typed_data';
 
 import 'package:analyzer/context/declared_variables.dart';
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1086 matching lines @@
     return serialized.map((error) {
       String errorName = error.uniqueName;
       ErrorCode errorCode =
           errorCodeByUniqueName(errorName) ?? _lintCodeByUniqueName(errorName);
       if (errorCode == null) {
         // This could fail because the error code is no longer defined, or, in
         // the case of a lint rule, if the lint rule has been disabled since the
         // errors were written.
         throw new StateError('No ErrorCode for $errorName in $file');
       }
-      return new AnalysisError.forValues(file.source, error.offset,
-          error.length, errorCode, error.message, error.correction);
+      return new AnalysisError.forValues(
+          file.source,
+          error.offset,
+          error.length,
+          errorCode,
+          error.message,
+          error.correction.isEmpty ? null : error.correction);
     }).toList();
   }
 
   /**
    * Return the key to store fully resolved results for the [signature].
    */
   String _getResolvedUnitKey(String signature) {
     return '$signature.resolved';
   }
 
@@ skipping 809 matching lines @@
           libraryDeclarations.add(new TopLevelDeclarationInSource(
               file.source, declaration, isExported));
         }
       }
     }
 
     // We're not done yet.
     return false;
   }
 }