Refactor runtime into libraries, better type reps

test/codegen/expect/8invalid-chars.in+file_name.js

Index: test/codegen/expect/8invalid-chars.in+file_name.js
diff --git a/test/codegen/expect/8invalid-chars.in+file_name.js b/test/codegen/expect/8invalid-chars.in+file_name.js
index 442e885d96b6d07d1ece7ddf143ded7a9628db01..506529070e54f5d285101e0a400ea8dcea317855 100644
--- a/test/codegen/expect/8invalid-chars.in+file_name.js
+++ b/test/codegen/expect/8invalid-chars.in+file_name.js
@@ -1,7 +1,9 @@
-dart.library('8invalid-chars.in+file_name', null, /* Imports */[
+dart_library.library('8invalid-chars.in+file_name', null, /* Imports */[
+  "dart_runtime/dart"
 ], /* Lazy imports */[
-], function(exports) {
+], function(exports, dart) {
   'use strict';
+  let dartx = dart.dartx;
   function main() {
   }
   dart.fn(main);