Make server use the common protocol classes

pkg/analysis_server/lib/src/analysis_server.dart

Index: pkg/analysis_server/lib/src/analysis_server.dart
diff --git a/pkg/analysis_server/lib/src/analysis_server.dart b/pkg/analysis_server/lib/src/analysis_server.dart
index 779beba850c003e1783e084bf26988f22be30f7e..352c0029c707cf18b51ea8b7ea21bef767586fb3 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -12,7 +12,7 @@ import 'dart:math' show max;
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
-    hide AnalysisOptions, Element;
+    hide AnalysisOptions;
 import 'package:analysis_server/src/analysis_logger.dart';
 import 'package:analysis_server/src/channel/channel.dart';
 import 'package:analysis_server/src/computer/computer_highlights.dart';
@@ -67,6 +67,7 @@ import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/src/util/glob.dart';
 import 'package:analyzer/task/dart.dart';
+import 'package:analyzer_plugin/protocol/protocol_common.dart' hide Element;
 import 'package:front_end/src/base/performace_logger.dart';
 import 'package:front_end/src/incremental/byte_store.dart';
 import 'package:front_end/src/incremental/file_byte_store.dart';
@@ -2188,7 +2189,7 @@ class ServerContextManagerCallbacks extends ContextManagerCallbacks {
     analysisServer.schedulePerformAnalysisOperation(context);
   }
 
-  List<server.HighlightRegion> _computeHighlightRegions(CompilationUnit unit) {
+  List<HighlightRegion> _computeHighlightRegions(CompilationUnit unit) {
     if (analysisServer.options.useAnalysisHighlight2) {
       return new DartUnitHighlightsComputer2(unit).compute();
     } else {