Add expectAsyncX and expectAsyncUntilX methods, and deprecate the old methods.

test/frontend/set_up_all_test.dart

Index: test/frontend/set_up_all_test.dart
diff --git a/test/frontend/set_up_all_test.dart b/test/frontend/set_up_all_test.dart
index 7ae113750795610bfde180b181d7bb62c56b67b8..a1f2cfc381e533be7ddbedb935c9943f9f663f71 100644
--- a/test/frontend/set_up_all_test.dart
+++ b/test/frontend/set_up_all_test.dart
@@ -204,7 +204,7 @@ void main() {
 
   test("isn't run for a skipped group", () async {
     // Declare this in the outer test so if it runs, the outer test will fail.
-    var shouldNotRun = expectAsync(() {}, count: 0);
+    var shouldNotRun = expectAsync0(() {}, count: 0);
 
     var engine = declareEngine(() {
       group("skipped", () {
@@ -279,7 +279,7 @@ void main() {
 
     test("doesn't run tests in the group", () async {
       // Declare this in the outer test so if it runs, the outer test will fail.
-      var shouldNotRun = expectAsync(() {}, count: 0);
+      var shouldNotRun = expectAsync0(() {}, count: 0);
 
       var engine = declareEngine(() {
         setUpAll(() => throw "error");
@@ -292,7 +292,7 @@ void main() {
 
     test("doesn't run inner groups", () async {
       // Declare this in the outer test so if it runs, the outer test will fail.
-      var shouldNotRun = expectAsync(() {}, count: 0);
+      var shouldNotRun = expectAsync0(() {}, count: 0);
 
       var engine = declareEngine(() {
         setUpAll(() => throw "error");
@@ -307,7 +307,7 @@ void main() {
 
     test("doesn't run further setUpAlls", () async {
       // Declare this in the outer test so if it runs, the outer test will fail.
-      var shouldNotRun = expectAsync(() {}, count: 0);
+      var shouldNotRun = expectAsync0(() {}, count: 0);
 
       var engine = declareEngine(() {
         setUpAll(() => throw "error");