perf(element binder): Do not create tasklists when not needed
perf(element binder): Do not create tasklists when not needed

This code was originally authored by @mhevery in the
DirectiveInjector change.

hitesh97/angular.dart,winstonewert/angular.dart,winstonewert/angular.dart,SibuStephen/angular.dart,trinarytree/angular.dart,giovannicandido/angular.dart,ronlobo/angular.dart,hitesh97/angular.dart,rkirov/angular.dart,hitesh97/angular.dart,SibuStephen/angular.dart,ronlobo/angular.dart,giovannicandido/angular.dart,winstonewert/angular.dart,winstonewert/angular.dart,rkirov/angular.dart,trinarytree/angular.dart,SibuStephen/angular.dart,ronlobo/angular.dart,hitesh97/angular.dart,SibuStephen/angular.dart,ronlobo/angular.dart,trinarytree/angular.dart,trinarytree/angular.dart,rkirov/angular.dart,giovannicandido/angular.dart,rkirov/angular.dart