Bug 946178, revert "Merge pull request #14259 from jaoo/933203" for Mnw bustage

This reverts commit 71e2fcdaf3a6b86d11645ab1163e037179f591a3, reversing
changes made to f9901db71b8e5a70da1700ae82b66231bc000660.
Bug 935177 - [Messages][Drafts] Update "discard message" confirmation prompt to options menu/dialog; add "save draft" no-op r=julienw

https://bugzilla.mozilla.org/show_bug.cgi?id=935177

- New strings:
  - save-as-draft      = Save as Draft
  - discard-message = Discard
- Removes window.confirm mechanism
- Implements Multi-option prompt with OptionMenu
- Basic tests to assert the correct operations are performed by the option handlers

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>
Bug 936641 - [Messages][Drafts] Create message drafts upon user interaction