Drupal behavior calls olark on pages where javascript hasn't been included

We hit a few pages (usually modal_frames) where the javascript code was included, but olark_code hadn't been added to the footer. The result was that the drupal behavior was trying to call olark() which hadn't been defined. On dev machines this was just a javascript error, but in production all our js is stored in one big file so this stopped it from running.

The quick fix was to check that olark() is a function before calling it. See patch in comments.