Format all tests.

tests/lib/async/stack_trace20_test.dart

Index: tests/lib/async/stack_trace20_test.dart
diff --git a/tests/lib/async/stack_trace20_test.dart b/tests/lib/async/stack_trace20_test.dart
index aaec9982b0e85947d03d53759706d16802f16fd4..b0420d4538dc8ad3e92cb4ea891ddd13e79fd2ea 100644
--- a/tests/lib/async/stack_trace20_test.dart
+++ b/tests/lib/async/stack_trace20_test.dart
@@ -22,13 +22,11 @@ main() {
     controller.close();
   });
   asyncStart();
-  controller.stream
-    .listen(null)
-    .asFuture()
-    .then((_) { throw "should never be reached"; },
-      onError: (e, st) {
-        Expect.equals("error", e);
-        Expect.identical(trace, st);
-        asyncEnd();
-      });
+  controller.stream.listen(null).asFuture().then((_) {
+    throw "should never be reached";
+  }, onError: (e, st) {
+    Expect.equals("error", e);
+    Expect.identical(trace, st);
+    asyncEnd();
+  });
 }