Replace bootstrap logic with 'boot.js', use 'component/dart' mime-type and add

pkg/polymer/lib/polymer.html

Index: pkg/polymer/lib/polymer.html
diff --git a/pkg/polymer/lib/polymer.html b/pkg/polymer/lib/polymer.html
index 9a90ea1a2c7672e36ca53d3c67a90ac50afd62e3..c4df6198c336710cda7a9d311030459ca52d103b 100644
--- a/pkg/polymer/lib/polymer.html
+++ b/pkg/polymer/lib/polymer.html
@@ -6,6 +6,11 @@
 
 <script src="src/js/use_native_dartium_shadowdom.js"></script>
 
+<!-- Bootstrap the user application in a new isolate. -->
+<script src="boot.js"></script>
+<!-- TODO(sigmund): replace boot.js by boot.dart (dartbug.com/18007)
+<script type="application/dart">export "package:polymer/boot.dart";</script>
+ -->
 <!--
 These two files are from the Polymer project:
 https://github.com/Polymer/platform/ and https://github.com/Polymer/polymer/.