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

sdk/lib/_internal/pub_generated/lib/src/barback.dart

Index: sdk/lib/_internal/pub_generated/lib/src/barback.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback.dart b/sdk/lib/_internal/pub_generated/lib/src/barback.dart
similarity index 98%
copy from sdk/lib/_internal/pub/lib/src/barback.dart
copy to sdk/lib/_internal/pub_generated/lib/src/barback.dart
index 33c775425b1e7f466570c8b83bed6e7d549c16a4..ea7e650557dd98a7c5cb9a20e52422a2364ca1ca 100644
--- a/sdk/lib/_internal/pub/lib/src/barback.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback.dart
@@ -51,7 +51,8 @@ Uri idToPackageUri(AssetId id) {
     throw new ArgumentError("Asset id $id doesn't identify a library.");
   }
 
-  return new Uri(scheme: 'package',
+  return new Uri(
+      scheme: 'package',
       path: p.url.join(id.package, id.path.replaceFirst('lib/', '')));
 }
 
@@ -79,8 +80,7 @@ AssetId packagesUrlToId(Uri url) {
   // There should be a package name after "packages".
   if (parts.length <= index + 1) {
     throw new FormatException(
-        'Invalid URL path "${url.path}". Expected package name '
-        'after "packages".');
+        'Invalid URL path "${url.path}". Expected package name ' 'after "packages".');
   }
 
   var package = parts[index + 1];