Remove an obsolete error from the spec and an obsolete command-line flag

pkg/analysis_server/lib/src/search/search_domain.dart

Index: pkg/analysis_server/lib/src/search/search_domain.dart
diff --git a/pkg/analysis_server/lib/src/search/search_domain.dart b/pkg/analysis_server/lib/src/search/search_domain.dart
index 3dffbad43496db4cc3203e763e21e2857cdb2b47..ee4f3da39525f18611b1b86002e886d9f5683928 100644
--- a/pkg/analysis_server/lib/src/search/search_domain.dart
+++ b/pkg/analysis_server/lib/src/search/search_domain.dart
@@ -180,9 +180,6 @@ class SearchDomainHandler implements protocol.RequestHandler {
 
   @override
   protocol.Response handleRequest(protocol.Request request) {
-    if (searchEngine == null) {
-      return new protocol.Response.noIndexGenerated(request);
-    }
     try {
       String requestName = request.method;
       if (requestName == SEARCH_FIND_ELEMENT_REFERENCES) {