remove comments in traverse.removeProperties

lib/6to5/traverse/index.js

@@ -80,6 +80,16 @@ traverse.removeProperties = function (tree) {
     delete node.start;
     delete node.end;
     delete node.loc;
+
+    clearComments(node.trailingComments);
+    clearComments(node.leadingComments);
+  };
+
+  var clearComments = function (comments) {
+    _.each(comments, function (comment) {
+      delete comment.extendedRange;
+      clear(comment);
+    });
   };
 
   clear(tree);