Use shared error for constructor's with return type.

pkg/compiler/lib/src/diagnostics/messages.dart

 // Copyright (c) 2011, 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.
 
 
 /**
  * The messages in this file should meet the following guide lines:
  *
  * 1. The message should be a complete sentence starting with an uppercase
  * letter, and ending with a period.
@@ skipping 1829 matching lines @@
           "Operator '#{operatorName}' must have exactly 2 parameters."),
 
       MessageKind.OPERATOR_OPTIONAL_PARAMETERS:
         const MessageTemplate(MessageKind.OPERATOR_OPTIONAL_PARAMETERS,
           "Operator '#{operatorName}' cannot have optional parameters."),
 
       MessageKind.OPERATOR_NAMED_PARAMETERS:
         const MessageTemplate(MessageKind.OPERATOR_NAMED_PARAMETERS,
           "Operator '#{operatorName}' cannot have named parameters."),
 
-      MessageKind.CONSTRUCTOR_WITH_RETURN_TYPE:
-        const MessageTemplate(MessageKind.CONSTRUCTOR_WITH_RETURN_TYPE,
-          "Cannot have return type for constructor."),
-
       MessageKind.CANNOT_RETURN_FROM_CONSTRUCTOR:
         const MessageTemplate(MessageKind.CANNOT_RETURN_FROM_CONSTRUCTOR,
           "Constructors can't return values.",
           howToFix: "Remove the return statement or use a factory constructor.",
           examples: const ["""
 class C {
   C() {
     return 1;
   }
 }
@@ skipping 1844 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }