Only send "analysis.analyzedFiles" notification when the set of files changes.

pkg/analysis_server/test/analysis_abstract.dart

Index: pkg/analysis_server/test/analysis_abstract.dart
diff --git a/pkg/analysis_server/test/analysis_abstract.dart b/pkg/analysis_server/test/analysis_abstract.dart
index 753a2f5fe333e2fcc9a5b65a0e82ea3ea38f00d1..539f71843f9ca8e36d663f913c0325f6a831884a 100644
--- a/pkg/analysis_server/test/analysis_abstract.dart
+++ b/pkg/analysis_server/test/analysis_abstract.dart
@@ -156,6 +156,13 @@ class AbstractAnalysisTest {
     }
   }
 
+  void removeGeneralAnalysisSubscription(GeneralAnalysisService service) {
+    generalServices.remove(service);
+    Request request = new AnalysisSetGeneralSubscriptionsParams(generalServices)
+        .toRequest('0');
+    handleSuccessfulRequest(request);
+  }
+
   void setUp() {
     serverChannel = new MockServerChannel();
     resourceProvider = new MemoryResourceProvider();