Incorrect logic in $field.change() can cause label to persist

I'm finding it hard to come up with creative titles for all these issues that are similar but different. This is sort of a combination of #461918: User Login Browser Auto-populate and #903122: Autofill can cause both password field value and password field label to appear concurrently. - caused by the former but related to the latter.

Anyway the expression if ($field != document.activeElement) is always true (in Firefox at least) because $field is a collection and document.activeElement is an object. This means that in Firefox when you focus a compact form field the label fades out but fades back in immediately after. The solution is to test $field[0]