Add support for a global configuration file.

test/runner/configuration/top_level_test.dart

Index: test/runner/configuration/top_level_test.dart
diff --git a/test/runner/configuration/top_level_test.dart b/test/runner/configuration/top_level_test.dart
index 445613d80ad7da85ad9d482cc37f0858c94bc7e6..8a219513aaa70b681ec26ed37b0f3fce49f4ec18 100644
--- a/test/runner/configuration/top_level_test.dart
+++ b/test/runner/configuration/top_level_test.dart
@@ -92,7 +92,7 @@ void main() {
       }
     """).create();
 
-    var test = runTest(["test.dart"], reporter: "compact");
+    var test = runTest(["test.dart"]);
     test.stdout.expect(consumeThrough(contains("dart:isolate-patch")));
     test.shouldExit(1);
   });