Fix 'Unused local variable' hints in analyzer and analysis_server.

pkg/analysis_server/test/services/correction/change_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.
 
 library test.services.correction.change;
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol_server.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 143 matching lines @@
   void test_editFromRange() {
     SourceRange range = new SourceRange(1, 2);
     SourceEdit edit = newSourceEdit_range(range, 'foo');
     expect(edit.offset, 1);
     expect(edit.length, 2);
     expect(edit.replacement, 'foo');
   }
 
   void test_eqEq() {
     SourceEdit a = new SourceEdit(1, 2, 'aaa');
-    SourceEdit a2 = new SourceEdit(1, 2, 'aaa');
-    SourceEdit b = new SourceEdit(1, 2, 'aaa');
     expect(a == a, isTrue);
     expect(a == new SourceEdit(1, 2, 'aaa'), isTrue);
     expect(a == this, isFalse);
     expect(a == new SourceEdit(1, 2, 'bbb'), isFalse);
     expect(a == new SourceEdit(10, 2, 'aaa'), isFalse);
   }
 
   void test_new() {
     SourceEdit edit = new SourceEdit(1, 2, 'foo', id: 'my-id');
     expect(edit.offset, 1);
@@ skipping 160 matching lines @@
 
   void test_toJson() {
     Position position = new Position('/test.dart', 1);
     var expectedJson = {
       FILE: '/test.dart',
       OFFSET: 1
     };
     expect(position.toJson(), expectedJson);
   }
 }