javascript diff_cleanupSemantic uses negative indexes in the equalities array

```
javascript diff_cleanupSemantic uses negative indexes in the equalities array.

This is because it equalitiesLength is allowed to go into a negative range.

Normally this doesn't cause any problems, because it will just be stored as a
property on the array, but Safari 1.5.x seems to have some issues and doesn't
always get the value that's stored in equalities[-1] back out. (Or perhaps it
didn't properly go in in some cases.)
```

Original issue reported on code.google.com by `d...@twkie.net` on 21 Jun 2013 at 10:48

Attachments:
- [diff_match_patch.js.patch](https://storage.googleapis.com/google-code-attachments/google-diff-match-patch/issue-89/comment-0/diff_match_patch.js.patch)

Inizia con il diff_match_patch.js.patch allegato e confrontalo con l’implementazione JavaScript di diff_cleanupSemantic presente nel repository. Verifica come viene aggiornato equalitiesLength e conferma che la modifica completata evita gli indici negativi nell’array delle uguaglianze, preservando al contempo il comportamento della pulizia semantica, inclusa la questione di compatibilità con Safari.

Scritto dal modello di indicizzazione a partire dal testo della issue.