Bug 890053 - [MMS][SMS] Regression. Recipients pull down pushes input behind keyboard

- broken display: https://www.dropbox.com/sh/pirp25nqtaqcktr/pfFsPQPG6n#f:1.jpg
- fixed display: https://www.dropbox.com/sh/pirp25nqtaqcktr/pfFsPQPG6n#f:2.jpg

https://bugzilla.mozilla.org/show_bug.cgi?id=890053
Signed-off-by: Rick Waldron <waldron.rick@gmail.com>