allow using code-prettify without dom

[winguse]

I love this project!

I am wondering if we can export some core functions to allow this project being used in server side project.

Say langHandlerForExtension here: https://github.com/google/code-prettify/blob/master/src/node_prettify.js#L1302

Now I simply make a private patch to make it work in my scenario.

diff --git a/src/node_prettify.js b/src/node_prettify.js
index df8d026..f69d10b 100644
--- a/src/node_prettify.js
+++ b/src/node_prettify.js
@@ -117,6 +117,7 @@ var prettyPrintOne;
  */
 var prettyPrint;

+var exportedLangHandlerForExtension;

 (function () {
   var win = (typeof window !== 'undefined') ? window : {};
@@ -1699,12 +1700,15 @@ var prettyPrint;
       return PR;
     });
   }
+
+  exportedLangHandlerForExtension = langHandlerForExtension;
 })();


 var path = require('path');

 module.exports = {
+  exportedLangHandlerForExtension,
   prettyPrint: prettyPrint,
   prettyPrintOne: prettyPrintOne,
   // include paths for css preprocessor support

It will be great if this is official supported.