fix files only containg comments not being output - fixes #259

lib/6to5/generation/generator.js

@@ -71,6 +71,12 @@ CodeGenerator.prototype.generate = function () {
 
   this.print(ast);
 
+  var comments = [];
+  _.each(ast.comments, function (comment) {
+    if (!comment._displayed) comments.push(comment);
+  });
+  if (comments.length) this._printComments(comments);
+
   return {
     map:  this.map.get(),
     code: this.buffer.get()
@@ -259,6 +265,8 @@ CodeGenerator.prototype._printComments = function (comments) {
   var self = this;
 
   _.each(comments, function (comment) {
+    comment._displayed = true;
+
     // whitespace before
     self.newline(self.whitespace.getNewlinesBefore(comment));