Add support for watch events and error notifications

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 2de4bbe8337a3181a5ed9795d81561e23fc61d7d..6f7938fe654f51ca78d87b8166ad363253e60715 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -69,6 +69,7 @@ import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/src/util/glob.dart';
 import 'package:analyzer/task/dart.dart';
 import 'package:plugin/plugin.dart';
+import 'package:watcher/watcher.dart';
 
 typedef void OptionUpdater(AnalysisOptionsImpl options);
 
@@ -2106,6 +2107,11 @@ class ServerContextManagerCallbacks extends ContextManagerCallbacks {
   }
 
   @override
+  void broadcastWatchEvent(WatchEvent event) {
+    analysisServer.pluginManager.broadcastWatchEvent(event);
+  }
+
+  @override
   void computingPackageMap(bool computing) =>
       analysisServer._computingPackageMap(computing);