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

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

Index: sdk/lib/_internal/pub_generated/lib/src/package_graph.dart
diff --git a/sdk/lib/_internal/pub/lib/src/package_graph.dart b/sdk/lib/_internal/pub_generated/lib/src/package_graph.dart
similarity index 91%
copy from sdk/lib/_internal/pub/lib/src/package_graph.dart
copy to sdk/lib/_internal/pub_generated/lib/src/package_graph.dart
index 02ba973bd1b4deeb6f51b06b6ce44b139c07b8bb..739a7d7433621da4a9904598e45226ba16cdd7d1 100644
--- a/sdk/lib/_internal/pub/lib/src/package_graph.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/package_graph.dart
@@ -46,8 +46,9 @@ class PackageGraph {
   TransformerCache loadTransformerCache() {
     if (_transformerCache == null) {
       if (entrypoint.root.dir == null) {
-        throw new StateError("Can't load the transformer cache for virtual "
-            "entrypoint ${entrypoint.root.name}.");
+        throw new StateError(
+            "Can't load the transformer cache for virtual "
+                "entrypoint ${entrypoint.root.name}.");
       }
       _transformerCache = new TransformerCache.load(this);
     }
@@ -63,9 +64,12 @@ class PackageGraph {
     if (package == entrypoint.root.name) return packages.values.toSet();
 
     if (_transitiveDependencies == null) {
-      var closure = transitiveClosure(mapMap(packages,
-          value: (_, package) => package.dependencies.map((dep) => dep.name)));
-      _transitiveDependencies = mapMap(closure,
+      var closure = transitiveClosure(
+          mapMap(
+              packages,
+              value: (_, package) => package.dependencies.map((dep) => dep.name)));
+      _transitiveDependencies = mapMap(
+          closure,
           value: (_, names) => names.map((name) => packages[name]).toSet());
     }