Do not override sane suffixes for hetero-lists

Review needed.

The original code wipes out `suffix` overwriting it by a value of name attribute that is not present, effectively throwing away the suffixes like `publisher` or `builder`. Moreover, the part that assigns numbers for colliding element names does not handle this situation correctly as the value of `suffix` becomes `""` in firefox 18 and `"null"` in chromium 26 and the corresponding paths can look like `"/hetero-list-add[]"`(ff) or `"/hetero-list-add[null]"`(chromium).

I propose to stick with the suffixes attached in `hetero-list.js` to avoid this incompatibility and have more descriptive paths (`/hetero-list-add[publisher]`) at the same time.