Remove ability to disable new analysis driver

pkg/analysis_server/lib/src/domain_diagnostic.dart

Index: pkg/analysis_server/lib/src/domain_diagnostic.dart
diff --git a/pkg/analysis_server/lib/src/domain_diagnostic.dart b/pkg/analysis_server/lib/src/domain_diagnostic.dart
index 8e6027ae202b7b40ac1da68a4d68f76b9f28d3ef..16aa7a98b7441984305fbfa1b249a948d2b2044f 100644
--- a/pkg/analysis_server/lib/src/domain_diagnostic.dart
+++ b/pkg/analysis_server/lib/src/domain_diagnostic.dart
@@ -37,14 +37,8 @@ class DiagnosticDomainHandler implements RequestHandler {
 
   /// Answer the `diagnostic.getDiagnostics` request.
   Response computeDiagnostics(Request request) {
-    List<ContextData> contexts = <ContextData>[];
-    if (server.options.enableNewAnalysisDriver) {
-      contexts = server.driverMap.values.map(extractDataFromDriver).toList();
-    } else {
-      for (AnalysisContext context in server.analysisContexts) {
-        contexts.add(extractDataFromContext(context));
-      }
-    }
+    List<ContextData> contexts =
+        server.driverMap.values.map(extractDataFromDriver).toList();
     return new DiagnosticGetDiagnosticsResult(contexts).toResponse(request.id);
   }