Clean up package imports and library names

pkg/analyzer/lib/src/generated/visitors.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 engine.ast.visitors;
+library analyzer.src.generated.visitors;
 
 import 'package:analyzer/src/generated/ast.dart';
 
 /// An [AstVisitor] that delegates calls to visit methods to all [delegates]
 /// before calling [visitChildren].
 class DelegatingAstVisitor<T> implements AstVisitor<T> {
   Iterable<AstVisitor<T>> _delegates;
   DelegatingAstVisitor(this._delegates);
 
   @override
@@ skipping 762 matching lines @@
     return null;
   }
 
   @override
   T visitYieldStatement(YieldStatement node) {
     _delegates.forEach((delegate) => delegate.visitYieldStatement(node));
     node.visitChildren(this);
     return null;
   }
 }