User for...in instead of for loop in iterate function

[davebriand]

I think it would be common to use store.remove inside store.iterate. If a for..in loop was used we could iterate and remove/delete keys.

Edit:
The issue is that currently a for loop is used, and as the number of keys changes (ie during a remove) so does the referenced length value, which means we won't be iterating through the entire collection. A for...in loop will iterate over all items in the collection even after a delete since it doesn't depend on the length of the collection.