Make sure we check the most up to date text for the token offsets.

The issue here was that we were using the old version of the editable string
(cached in var text) to look for the start/end of tokens, but the result
of calling commitChip may have updated the text (added corrective rfc822
formatting, or a display name)

Fixes b/7268603 [Manta] List of email addresses pasted into the To field is broken

Change-Id: Iccc8dbf78a018c84fd818582d10ff2b02a787276