ProcessDialog: "Other" action buttons should be framed.

Follows-up 3ba36b9a53.

Safe buttons and special buttons need not be framed (given their
position), however regular buttons in the footer are supposed to
be framed.

This was the case in the original patchset, but accidentally
removed in a rebase along the way:
 https://gerrit.wikimedia.org/r/#/c/139550/41..42/src/dialogs/ProcessDialog.js

Change-Id: If1d8993f97dcf67d2c2d206a9a94f4569904637b