Facebook token widget broken on Activity form

The widget for selecting With and Assignee contacts is broken in my 3.4.x SVN install. Not sure which commit caused the problem, but recent one ??

When I load the form - to add a Meeting for example - (civicrm/activity/add?action=add&reset=1&cid=63&selectedChild=activity&atype=1), the widget doesn't load and I get this jScript error:

Error: missing ; before statement
Source File: http://localhost/dgg/d634/civicrm/activity/add?action=add&reset=1&cid=63&selectedChild=activity&atype=1
Line: 458, Column: 44
Source Code:
target_contact = '{"name":"'"[

{"id":63,"name":"Adams, Dan"}

]"'","id":"'"0"+'"},';