Add a message for analysis server to indicate a successful connection.

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 1c9004ff8f00488234924bf913fead6c72cc9884..5a09a3639ef2232cf1a018df308133e821498417 100644
--- a/pkg/analysis_server/lib/src/analysis_server.dart
+++ b/pkg/analysis_server/lib/src/analysis_server.dart
@@ -32,6 +32,11 @@ class AnalysisServer {
   static const String SOURCE_PARAM = 'source';
 
   /**
+   * The name of the connected result value.
+   */
+  static const String CONNECTED_RESULT = 'connected';
+
+  /**
    * The channel from which requests are received and to which responses should
    * be sent.
    */
@@ -66,6 +71,9 @@ class AnalysisServer {
   AnalysisServer(this.channel) {
     AnalysisEngine.instance.logger = new AnalysisLogger();
     running = true;
+    Response response = new Response('');
+    response.setResult(CONNECTED_RESULT, true);
+    channel.sendResponse(response);
     channel.listen(handleRequest, onDone: done, onError: error);
   }