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

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

Index: sdk/lib/_internal/pub_generated/lib/src/barback/transformer_cache.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/transformer_cache.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_cache.dart
similarity index 92%
copy from sdk/lib/_internal/pub/lib/src/barback/transformer_cache.dart
copy to sdk/lib/_internal/pub_generated/lib/src/barback/transformer_cache.dart
index e6c9a538acc4d32e015626cea801084b4b3762d4..7e8a61d90c76b2c53a97bc1bd1c39600fd89d147 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/transformer_cache.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/transformer_cache.dart
@@ -60,8 +60,8 @@ class TransformerCache {
       // that's fine; we just won't load them.
       if (!_graph.packages.containsKey(id.package)) return new Set();
 
-      return _graph.transitiveDependencies(id.package)
-          .map((package) => package.name).toSet();
+      return _graph.transitiveDependencies(
+          id.package).map((package) => package.name).toSet();
     }));
 
     // If none of the snapshot's dependencies have changed, then we can reuse
@@ -112,16 +112,17 @@ class TransformerCache {
     if (_oldTransformers.containsAll(_newTransformers)) return;
 
     ensureDir(_dir);
-    writeTextFile(_manifestPath,
+    writeTextFile(
+        _manifestPath,
         "${sdk.version}\n" +
-        ordered(_newTransformers.map((id) => id.serialize())).join(","));
+            ordered(_newTransformers.map((id) => id.serialize())).join(","));
   }
 
   /// Parses the cache manifest and returns the set of previously-cached
   /// transformers.
   ///
   /// If the manifest indicates that the SDK version is out-of-date, this
-  /// deletes the existing cache. Otherwise, 
+  /// deletes the existing cache. Otherwise,
   Set<TransformerId> _parseManifest() {
     if (!fileExists(_manifestPath)) return new Set();
 
@@ -137,8 +138,7 @@ class TransformerCache {
 
     /// The second line of the manifest is a list of transformer ids used to
     /// create the existing snapshot.
-    return manifest.single.split(",")
-        .map((id) => new TransformerId.parse(id, null))
-        .toSet();
+    return manifest.single.split(
+        ",").map((id) => new TransformerId.parse(id, null)).toSet();
   }
 }