removed global dependency from grammer

lib/coffee-script.js

@@ -5,7 +5,6 @@
     Lexer = require('./lexer').Lexer;
     parser = require('./parser').parser;
     helpers = require('./helpers').helpers;
-    helpers.extend(global, require('./nodes'));
     if (require.extensions) {
       fs = require('fs');
       require.extensions['.coffee'] = function(module, filename) {
@@ -73,4 +72,5 @@
       return "";
     }
   };
+  parser.yy = require('./nodes');
 })();