Clean up imports in analysis_server and analyzer_cli (and one missed in analyzer)

pkg/analysis_server/lib/src/services/search/element_visitors.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 services.search.element_visitors;
 
-import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/visitor.dart';
 
 /**
  * Uses [processor] to visit all of the children of [element].
  * If [processor] returns `true`, then children of a child are visited too.
  */
 void visitChildren(Element element, ElementProcessor processor) {
   element.visitChildren(new _ElementVisitorAdapter(processor));
 }
 
 /**
@@ skipping 37 matching lines @@
 
   @override
   void visitElement(Element element) {
     if (element is CompilationUnitElement) {
       element.visitChildren(this);
     } else {
       processor(element);
     }
   }
 }