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

pkg/analysis_server/lib/protocol/protocol.dart

Index: pkg/analysis_server/lib/protocol/protocol.dart
diff --git a/pkg/analysis_server/lib/protocol/protocol.dart b/pkg/analysis_server/lib/protocol/protocol.dart
index b1c720a5f02fb8d2ccad1a59e952c417143366ec..79a07bd2e82adf0e3a0e9d30d8ad423efec45dae 100644
--- a/pkg/analysis_server/lib/protocol/protocol.dart
+++ b/pkg/analysis_server/lib/protocol/protocol.dart
@@ -478,15 +478,6 @@ class Response {
                 RequestErrorCode.INVALID_REQUEST, 'Invalid request'));
 
   /**
-   * Initialize a newly created instance to represent an error condition caused
-   * by a request that requires an index, but indexing is disabled.
-   */
-  Response.noIndexGenerated(Request request)
-      : this(request.id,
-            error: new RequestError(
-                RequestErrorCode.NO_INDEX_GENERATED, 'Indexing is disabled'));
-
-  /**
    * Initialize a newly created instance to represent the
    * ORGANIZE_DIRECTIVES_ERROR error condition.
    */