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

sdk/lib/_internal/pub_generated/test/barback/utils.dart

Index: sdk/lib/_internal/pub_generated/test/barback/utils.dart
diff --git a/sdk/lib/_internal/pub/test/barback/utils.dart b/sdk/lib/_internal/pub_generated/test/barback/utils.dart
similarity index 80%
copy from sdk/lib/_internal/pub/test/barback/utils.dart
copy to sdk/lib/_internal/pub_generated/test/barback/utils.dart
index e4d9efed5c02a92d8a7714e91ae355f3108f94b6..ebdfd426275e3987f98f1dda8497bdd69375801a 100644
--- a/sdk/lib/_internal/pub/test/barback/utils.dart
+++ b/sdk/lib/_internal/pub_generated/test/barback/utils.dart
@@ -32,29 +32,29 @@ void pubBuildAndServeShouldFail(String description, {List<String> args,
   var buildExpectation = buildError;
   var serveExpectation = serveError;
   if (exitCode == exit_codes.USAGE) {
-    buildExpectation = allOf(
-        startsWith(buildExpectation), contains("Usage: pub build"));
-    serveExpectation = allOf(
-        startsWith(serveExpectation), contains("Usage: pub serve"));
+    buildExpectation =
+        allOf(startsWith(buildExpectation), contains("Usage: pub build"));
+    serveExpectation =
+        allOf(startsWith(serveExpectation), contains("Usage: pub serve"));
   }
 
   integration("build fails $description", () {
-    schedulePub(args: ["build"]..addAll(args),
+    schedulePub(
+        args: ["build"]..addAll(args),
         error: buildExpectation,
         exitCode: exitCode);
   });
 
   integration("build --format json fails $description", () {
-    schedulePub(args: ["build", "--format", "json"]..addAll(args),
-        outputJson: {
-          "error": buildError // No usage in JSON output.
-        },
-        exitCode: exitCode);
+    schedulePub(args: ["build", "--format", "json"]..addAll(args), outputJson: {
+      "error": buildError // No usage in JSON output.
+    }, exitCode: exitCode);
   });
 
   integration("serve fails $description", () {
-    schedulePub(args: ["serve"]..addAll(args),
+    schedulePub(
+        args: ["serve"]..addAll(args),
         error: serveExpectation,
         exitCode: exitCode);
   });
-}
+}