Fix analyzer warnings in a test.

runtime/observatory/tests/service/regress_28980_test.dart

Index: runtime/observatory/tests/service/regress_28980_test.dart
diff --git a/runtime/observatory/tests/service/regress_28980_test.dart b/runtime/observatory/tests/service/regress_28980_test.dart
index 79eb64449a2dcf1437ea57ee2ffab6caf392581a..2131225c60a0d4c76a5e5069e4e5ca5063d9e010 100644
--- a/runtime/observatory/tests/service/regress_28980_test.dart
+++ b/runtime/observatory/tests/service/regress_28980_test.dart
@@ -38,8 +38,8 @@ Future<Null> test_code() async {
       locked = true; // LINE_B
     } on FileSystemException {
       if (!printed) {
-        printTrace('Print path: ${_lock.path}');
-        printStatus('Just another line...');
+        print('Print path: ${_lock.path}');
+        print('Just another line...');
         printed = true;
       }
       await new Future<Null>.delayed(const Duration(milliseconds: 50));