Make server use the common protocol classes

pkg/analysis_server/lib/plugin/protocol/protocol_dart.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.
 
 /**
  * Utilities for converting Dart entities into analysis server's protocol
  * entities.
  */
-library analysis_server.plugin.protocol.protocol_dart;
-
-import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/protocol_server.dart';
 import 'package:analyzer/dart/element/element.dart' as engine;
 import 'package:analyzer/src/generated/utilities_dart.dart' as engine;
+import 'package:analyzer_plugin/protocol/protocol_common.dart';
 
 /**
  * Return a protocol [Element] corresponding to the given [engine.Element].
  */
 Element convertElement(engine.Element element) {
   String name = element.displayName;
   String elementTypeParameters = _getTypeParametersString(element);
   String elementParameters = _getParametersString(element);
   String elementReturnType = getReturnTypeString(element);
   ElementKind kind = convertElementToElementKind(element);
@@ skipping 184 matching lines @@
 bool _isStatic(engine.Element element) {
   // TODO(scheglov) add isStatic to Element API
   if (element is engine.ExecutableElement) {
     return element.isStatic;
   }
   if (element is engine.PropertyInducingElement) {
     return element.isStatic;
   }
   return false;
 }