improve analysis server notifications

pkg/analysis_server/lib/src/domain_server.dart

Index: pkg/analysis_server/lib/src/domain_server.dart
diff --git a/pkg/analysis_server/lib/src/domain_server.dart b/pkg/analysis_server/lib/src/domain_server.dart
index 495024a9dc715679db8da8de19fbf23cc461a316..e213bdd7a904d2d811b4609f7a65915cbc22a77f 100644
--- a/pkg/analysis_server/lib/src/domain_server.dart
+++ b/pkg/analysis_server/lib/src/domain_server.dart
@@ -111,6 +111,7 @@ class ServerDomainHandler implements RequestHandler {
       // new PackageUriResolver(),
     ]);
     server.contextMap[contextId] = context;
+    server.contextIdMap[context] = contextId;
 
     Response response = new Response(request.id);
     return response;
@@ -127,6 +128,7 @@ class ServerDomainHandler implements RequestHandler {
     if (removedContext == null) {
       return new Response.contextDoesNotExist(request);
     }
+    server.contextIdMap.remove(removedContext);
     Response response = new Response(request.id);
     return response;
   }