Move sunflower to a new directory, make final tweaks to make it all work.

lib/runtime/dart_runtime.js

Index: lib/runtime/dart_runtime.js
diff --git a/lib/runtime/dart_runtime.js b/lib/runtime/dart_runtime.js
index 39c042368dfdaf4d9e2d036efb4772e9b05dc7e6..600bb8c45ee58219a09e7513321f69eec8d3f68c 100644
--- a/lib/runtime/dart_runtime.js
+++ b/lib/runtime/dart_runtime.js
@@ -2,6 +2,10 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// TODO(jmesserly, sigmund): remove these two lines:
+var math = Math;
+var core = core || {int: { parse: Number }, print: e => console.log(e) };
+
 var dart;
 (function (dart) {
   var defineProperty = Object.defineProperty;