Fix hints in the analyzer package.

pkg/analyzer/test/generated/element_test.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.element_test;
 
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 3768 matching lines @@
     _uA = UnionTypeImpl.union([_typeA]);
     _uB = UnionTypeImpl.union([_typeB]);
     _uAB = UnionTypeImpl.union([_typeA, _typeB]);
     _uBA = UnionTypeImpl.union([_typeB, _typeA]);
     _us = <DartType>[_uA, _uB, _uAB, _uBA];
   }
 
   void test_emptyUnionsNotAllowed() {
     try {
       UnionTypeImpl.union([]);
-    } on IllegalArgumentException catch (e) {
+    } on IllegalArgumentException {
       return;
     }
     fail("Expected illegal argument exception.");
   }
 
   void test_equality_beingASubtypeOfAnElementIsNotSufficient() {
     // Non-equal if some elements are different
     expect(_uAB == _uA, isFalse);
   }
 
@@ skipping 185 matching lines @@
 }
 
 class _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction
     extends InterfaceTypeImpl {
   _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction(ClassElement arg0)
       : super.con1(arg0);
 
   @override
   bool get isDartCoreFunction => true;
 }