Insert tokens in Plain Text message body IE8 - token not inserted at cursor position and content is duplicated

This bug has been reported in IE8 only. It affects the Plain-text Message field in Step 3 of the New Mailing Wizard.

1. Token is NOT inserted at cursor position (AFTER 1st token insert action)
2. ... and (more importantly) existing content is duplicated when you do token insert actions (I think this also happens on the second token insert action and beyond).

Log time spent and record to Bluebird issue: http://senatedev.senate.state.ny.us/issues/show/3524