[dart2js] include dart:_js_annotations into the platform file by default

Change-Id: I7d93347cc41e344213a5c62f72638d4d2fd18728
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153366
Reviewed-by: Stephen Adams <[email protected]>
Commit-Queue: Sigmund Cherem <[email protected]>

Author: sigmundch

pkg/compiler/lib/src/kernel/dart2js_target.dart

@@ -182,6 +182,7 @@ const _requiredLibraries = const <String, List<String>>{
     'dart:_foreign_helper',
     'dart:_interceptors',
     'dart:_internal',
+    'dart:_js_annotations',
     'dart:_js_embedded_names',
     'dart:_js_helper',
     'dart:_js_names',
@@ -203,6 +204,7 @@ const _requiredLibraries = const <String, List<String>>{
     'dart:_foreign_helper',
     'dart:_interceptors',
     'dart:_internal',
+    'dart:_js_annotations',
     'dart:_js_embedded_names',
     'dart:_js_helper',
     'dart:_js_names',