Refactor runtime into libraries, better type reps

lib/runtime/dart/_foreign_helper.js

Index: lib/runtime/dart/_foreign_helper.js
diff --git a/lib/runtime/dart/_foreign_helper.js b/lib/runtime/dart/_foreign_helper.js
index bea05ed2c965e15ac4da5fe7292524a953aca954..9dc1deeef9c779af01f7125975720d5ce7e0f7fa 100644
--- a/lib/runtime/dart/_foreign_helper.js
+++ b/lib/runtime/dart/_foreign_helper.js
@@ -1,8 +1,10 @@
-dart.library('dart/_foreign_helper', null, /* Imports */[
+dart_library.library('dart/_foreign_helper', null, /* Imports */[
+  "dart_runtime/dart",
   'dart/core'
 ], /* Lazy imports */[
-], function(exports, core) {
+], function(exports, dart, core) {
   'use strict';
+  let dartx = dart.dartx;
   function JS(typeDescription, codeTemplate, arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10, arg11) {
     if (arg0 === void 0)
       arg0 = null;