cleanup: removed an invalid export

Author: vsavkin

modules/angular2/di.ts

@@ -35,7 +35,6 @@ export {Key, KeyRegistry, TypeLiteral} from './src/di/key';
 export {
  NoBindingError,
  AbstractBindingError,
- AsyncBindingError,
  CyclicDependencyError,
  InstantiationError,
  InvalidBindingError,