Fix a couple of references in _runtime that should have been resolved as quasiquotes

tool/input_sdk/private/generators.dart

Index: tool/input_sdk/private/generators.dart
diff --git a/tool/input_sdk/private/generators.dart b/tool/input_sdk/private/generators.dart
index 84c594303df5f11e0d7f42766833ee52a0387ebb..6203f71973b5e16da645f6af929f7197c7d6af3d 100644
--- a/tool/input_sdk/private/generators.dart
+++ b/tool/input_sdk/private/generators.dart
@@ -219,5 +219,5 @@ final _AsyncStarStreamController = JS('', '''
 /// Returns a Stream of T implemented by an async* function. */
 ///
 asyncStar(gen, T, @rest args) => JS('', '''(() => {
-  return new _AsyncStarStreamController($gen, $T, $args).controller.stream;
+  return new $_AsyncStarStreamController($gen, $T, $args).controller.stream;
 })()''');