remove unused imports

pkg/analyzer/lib/src/services/lint.dart

 // Copyright (c) 2015, 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 lint;
 
 import 'package:analyzer/src/generated/ast.dart';
-import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/visitors.dart';
 
 
 /// Implementers contribute lint warnings via the provided error [reporter].
 abstract class Linter {
   /// Used to report lint warnings.
   /// NOTE: this is set by the framework before visit begins.
@@ skipping 32 matching lines @@
     });
   }
 
   void _generate(CompilationUnit unit, Source source) {
     ErrorReporter errorReporter = new ErrorReporter(_errorListener, source);
     _linters.forEach((l) => l.reporter = errorReporter);
     Iterable<AstVisitor> visitors = _linters.map((l) => l.getVisitor());
     unit.accept(new DelegatingAstVisitor(visitors.where((v) => v != null)));
   }
 }