More strong mode changes in analysis_server

pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart

Index: pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart
diff --git a/pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart b/pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart
index 3d1886569c8255cbf2691b1fd6c58f142bd28f6c..3e3af149490f18db2d7157fd4dd079002ea3d151 100644
--- a/pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart
+++ b/pkg/analysis_server/benchmark/perf/analysis_timing_tests.dart
@@ -30,7 +30,10 @@ main(List<String> arguments) {
   }
   source = args[SOURCE_OPTION];
   priorityFile = args[PRIORITY_FILE_OPTION];
-  metricNames.addAll(args[METRIC_NAME_OPTION]);
+  List names = args[METRIC_NAME_OPTION] as List;
+  for (var name in names) {
+    metricNames.add(name as String);
+  }
   unittestConfiguration.timeout = new Duration(minutes: 20);
 
   var test;