Report separate UNUSED_CATCH_CLAUSE and UNUSED_CATCH_STACK hints.

pkg/analyzer/lib/src/generated/error.dart

 // Copyright (c) 2014, 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 engine.error;
 
 import 'dart:collection';
 
 import 'ast.dart' show AstNode;
 import 'element.dart';
@@ skipping 2959 matching lines @@
   static const HintCode UNUSED_FIELD = const HintCode(
       'UNUSED_FIELD', "The value of the field '{0}' is not used");
 
   /**
    * Unused imports are imports which are never used.
    */
   static const HintCode UNUSED_IMPORT =
       const HintCode('UNUSED_IMPORT', "Unused import");
 
   /**
+   * Unused catch exception variables.
+   */
+  static const HintCode UNUSED_CATCH_CLAUSE = const HintCode(
+      'UNUSED_CATCH_CLAUSE',
+      "The exception variable '{0}' is not used, so the 'catch' clause can be removed");
+
+  /**
+   * Unused catch stack trace variables.
+   */
+  static const HintCode UNUSED_CATCH_STACK = const HintCode(
+      'UNUSED_CATCH_STACK',
+      "The stack trace variable '{0}' is not used and can be removed");
+
+  /**
    * Unused local variables are local varaibles which are never read.
    */
   static const HintCode UNUSED_LOCAL_VARIABLE = const HintCode(
       'UNUSED_LOCAL_VARIABLE',
       "The value of the local variable '{0}' is not used");
 
   /**
    * Hint for cases where the source expects a method or function to return a
    * non-void result, but the method or function signature returns void.
    *
@@ skipping 1870 matching lines @@
    * Initialize a newly created error code to have the given [name].
    */
   const TodoCode(String name) : super(name, "{0}");
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
 
   @override
   ErrorType get type => ErrorType.TODO;
 }