I am after removing a bit of clutter from show_bug.cgi.
Mobile team prefers to keep Mobile Platform separate from Platform:
"we don't want *any* desktop os in the platform, they're useless to us. it'll be pure noise to have the desktop os list."
Hence we should show the "Mobile Platform" custom field only for products "Wikipedia App"/"Wiktionary App"/"WikiLoves Monuments Mobile" and for component "MobileFrontend".
This requires Bugzilla 4.2 as per https://bugzilla.mozilla.org/show_bug.cgi?id=479400 .