In the change screen, after clicking on an element of the 'Add
Reviewer' suggestion list, users expect to be able to add the reviewer
by hitting enter. This did not work in Firefox, as after clicking on
an entry in the suggestion list, the body got focused. By setting the
focus on the 'Add reviewer's text box after selecting a suggestion
list item, we now allow users to add the reviewer by hitting enter.
Change-Id: I50ab4f80107f606f97260d48fc770672b829ea38