Fix errors and warnings

pkg/analyzer/test/src/summary/resynthesize_ast_test.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.
 
 library analyzer.test.src.summary.resynthesize_ast_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/dart/element/element.dart';
@@ skipping 677 matching lines @@
     super.test_unsafeBlockClosureInference_methodCall_implicitTypeParam();
   }
 
   @override
   @failingTest
   void test_unsafeBlockClosureInference_methodCall_implicitTypeParam_comment() {
     super
         .test_unsafeBlockClosureInference_methodCall_implicitTypeParam_comment();
   }
 
-  @override
   LibraryElementImpl _checkSource(
       SummaryResynthesizer resynthesizer, Source source) {
     LibraryElementImpl resynthesized =
         resynthesizer.getLibraryElement(source.uri.toString());
     LibraryElementImpl original = context.computeLibraryElement(source);
     checkLibraryElements(original, resynthesized);
     return resynthesized;
   }
 }
 
@@ skipping 227 matching lines @@
   }
 
   @override
   DartSdk createDartSdk() => AbstractContextTest.SHARED_MOCK_SDK;
 
   @override
   TestSummaryResynthesizer encodeDecodeLibrarySource(Source source) {
     return _encodeLibrary(source);
   }
 }