Fixing a typo (#597)

diff --git a/lib/src/analysis_server.dart b/lib/src/analysis_server.dart
index 7cfccd9..35ec013 100644
--- a/lib/src/analysis_server.dart
+++ b/lib/src/analysis_server.dart
@@ -86,7 +86,7 @@
   }
 
   Future warmup() => Future.wait(<Future<dynamic>>[
-        _flutterWebManager.warmup(),
+        _flutterAnalysisServer.warmup(),
         _dartAnalysisServer.warmup(),
       ]);