fixes #69, avoid module name inside module scope

test/codegen/expect/html_input_d/html_input_d.js

 var html_input_d;
-(function(html_input_d) {
+(function(exports) {
   'use strict';
   // Function fib: (int) → int
   function fib(n) {
     return _fib(n, new core.Map());
   }
   // Function _fib: (int, Map<int, int>) → int
   function _fib(n, seen) {
     if (dart.notNull(n === 0) || dart.notNull(n === 1))
       return 1;
     if (seen.get(n) !== null)
       return seen.get(n);
     seen.set(n, _fib(n - 1, seen) + _fib(n - 2, seen));
     return seen.get(n);
   }
   // Exports:
-  html_input_d.fib = fib;
+  exports.fib = fib;
 })(html_input_d || (html_input_d = {}));