Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/test/transformer/exclusion/exclude_asset_prefix_test.dart

Index: sdk/lib/_internal/pub_generated/test/transformer/exclusion/exclude_asset_prefix_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/exclusion/exclude_asset_prefix_test.dart b/sdk/lib/_internal/pub_generated/test/transformer/exclusion/exclude_asset_prefix_test.dart
similarity index 64%
copy from sdk/lib/_internal/pub/test/transformer/exclusion/exclude_asset_prefix_test.dart
copy to sdk/lib/_internal/pub_generated/test/transformer/exclusion/exclude_asset_prefix_test.dart
index 6e2cfaca0da2e8a90bc4addf3e2b6393e3831da7..12bbfd2c308e4a076c6bea7f979122ea2098d9de 100644
--- a/sdk/lib/_internal/pub/test/transformer/exclusion/exclude_asset_prefix_test.dart
+++ b/sdk/lib/_internal/pub_generated/test/transformer/exclusion/exclude_asset_prefix_test.dart
@@ -12,31 +12,22 @@ main() {
   initConfig();
   withBarbackVersions("any", () {
     integration("allows a directory prefix to exclude", () {
-      d.dir(appPath, [
-        d.pubspec({
+      d.dir(appPath, [d.pubspec({
           "name": "myapp",
-          "transformers": [
-            {
+          "transformers": [{
               "myapp/src/transformer": {
                 "\$exclude": "web/sub"
               }
-            }
-          ]
+            }]
         }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", REWRITE_TRANSFORMER)
-        ])]),
-        d.dir("web", [
-          d.file("foo.txt", "foo"),
-          d.file("bar.txt", "bar"),
-          d.dir("sub", [
-            d.file("foo.txt", "foo"),
-          ]),
-          d.dir("subbub", [
-            d.file("foo.txt", "foo"),
-          ])
-        ])
-      ]).create();
+            d.dir("lib", [d.dir("src", [d.file("transformer.dart", REWRITE_TRANSFORMER)])]),
+            d.dir(
+                "web",
+                [
+                    d.file("foo.txt", "foo"),
+                    d.file("bar.txt", "bar"),
+                    d.dir("sub", [d.file("foo.txt", "foo"),]),
+                    d.dir("subbub", [d.file("foo.txt", "foo"),])])]).create();
 
       createLockFile('myapp', pkg: ['barback']);