Use the polling watcher by default in pub tests for now.

sdk/lib/_internal/pub/test/serve/native_watch_removed_file_test.dart

Index: sdk/lib/_internal/pub/test/serve/native_watch_removed_file_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart b/sdk/lib/_internal/pub/test/serve/native_watch_removed_file_test.dart
similarity index 75%
copy from sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart
copy to sdk/lib/_internal/pub/test/serve/native_watch_removed_file_test.dart
index 46fdc4cde14951770a824cddacad78b3ceac5a1b..271842ef6611d29c2c1434c8984072e876e4740e 100644
--- a/sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart
+++ b/sdk/lib/_internal/pub/test/serve/native_watch_removed_file_test.dart
@@ -12,9 +12,13 @@ import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
+// TODO(nweiz): Default to testing the native watcher and add an explicit test
+// for the polling watcher when issue 14941 is fixed.
+
 main() {
   initConfig();
-  integration("stop serving a file that is removed", () {
+  integration("stop serving a file that is removed when using the native "
+      "watcher", () {
     d.dir(appPath, [
       d.appPubspec(),
       d.dir("web", [
@@ -22,7 +26,7 @@ main() {
       ])
     ]).create();
 
-    startPubServe();
+    pubServe(args: ["--no-force-poll"]);
     requestShouldSucceed("index.html", "body");
 
     schedule(() => deleteEntry(