Log only valid occurences of 'All native types used ...'.

tests/compiler/dart2js/all_native_test.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/common/names.dart';
+import 'package:compiler/src/commandline_options.dart';
+import 'package:expect/expect.dart';
+import 'memory_compiler.dart';
+
+main() {
+  asyncTest(() async {
+    DiagnosticCollector collector = new DiagnosticCollector();
+    await runCompiler(
+        entryPoint: Uris.dart_html,
+        diagnosticHandler: collector,
+        options: [Flags.analyzeAll, Flags.verbose]);
+    int allNativeUsedCount =
+        collector.verboseInfos.where((CollectedMessage message) {
+      return message.text.startsWith('All native types marked as used due to ');
+    }).length;
+    Expect.equals(
+        1, allNativeUsedCount, "Unexpected message count: $allNativeUsedCount");

[Johnni Winther, 2016/12/14 09:00:10]

Count before the change was 7441!

+  });
+}