Refactor runtime into libraries, better type reps

test/codegen/expect/sunflower/sunflower.js

Index: test/codegen/expect/sunflower/sunflower.js
diff --git a/test/codegen/expect/sunflower/sunflower.js b/test/codegen/expect/sunflower/sunflower.js
index 5dc7175b95dbe9c9e4497a8c323f069016e6e6ea..aae61805bef4c1a541aa3c937abfc368ac0d3a01 100644
--- a/test/codegen/expect/sunflower/sunflower.js
+++ b/test/codegen/expect/sunflower/sunflower.js
@@ -1,12 +1,14 @@
-dart.library('sunflower', null, /* Imports */[
+dart_library.library('sunflower', null, /* Imports */[
+  "dart_runtime/dart",
   'dom',
   'dart/core',
   'dart/math',
   'painter',
   'circle'
 ], /* Lazy imports */[
-], function(exports, dom, core, math, painter, circle) {
+], function(exports, dart, dom, core, math, painter, circle) {
   'use strict';
+  let dartx = dart.dartx;
   let SEED_RADIUS = 2;
   let SCALE_FACTOR = 4;
   let MAX_D = 300;