Don't remove indexing operations on potential source changes.

pkg/analysis_server/lib/src/operation/operation_analysis.dart

Index: pkg/analysis_server/lib/src/operation/operation_analysis.dart
diff --git a/pkg/analysis_server/lib/src/operation/operation_analysis.dart b/pkg/analysis_server/lib/src/operation/operation_analysis.dart
index 4ed7609da911865f6f7ca37c153fab9fa8df9f3b..a2f9c260fa3f2b8f14cd852e0041863ff2f53bb3 100644
--- a/pkg/analysis_server/lib/src/operation/operation_analysis.dart
+++ b/pkg/analysis_server/lib/src/operation/operation_analysis.dart
@@ -21,6 +21,15 @@ import 'package:analyzer/src/generated/source.dart';
 
 
 /**
+ * Schedules indexing of the given [file] using the resolved [dartUnit].
+ */
+void scheduleIndexOperation(AnalysisServer server, String file,
+    AnalysisContext context, CompilationUnit dartUnit) {
+  server.addOperation(new _DartIndexOperation(context, file, dartUnit));
+}
+
+
+/**
  * Schedules sending notifications for the given [file] using the resolved
  * [resolvedDartUnit].
  */