Rework instrumentation API

pkg/analysis_server/test/domain_analysis_test.dart

Index: pkg/analysis_server/test/domain_analysis_test.dart
diff --git a/pkg/analysis_server/test/domain_analysis_test.dart b/pkg/analysis_server/test/domain_analysis_test.dart
index 6f242c1e820a97fcdffd38764e081b06c6bf18db..2472e67e2c9e4f962c3e5f9767b1c297caf25e47 100644
--- a/pkg/analysis_server/test/domain_analysis_test.dart
+++ b/pkg/analysis_server/test/domain_analysis_test.dart
@@ -41,7 +41,7 @@ main() {
         null,
         new AnalysisServerOptions(),
         new MockSdk(),
-        new NullInstrumentationServer());
+        InstrumentationService.NULL_SERVICE);
     handler = new AnalysisDomainHandler(server);
   });
 
@@ -464,7 +464,7 @@ class AnalysisTestHelper {
         null,
         new AnalysisServerOptions(),
         new MockSdk(),
-        new NullInstrumentationServer());
+        InstrumentationService.NULL_SERVICE);
     handler = new AnalysisDomainHandler(server);
     // listen for notifications
     Stream<Notification> notificationStream =