Merge pull request #12856 from Neeraj-Seth/bug-890207_cursor_hide_issue

Bug 890207 - [B2G][Gaia][Keyboard][Auto-correction] If a wording include...(cherry picked from commit 37032f754c7186a9e7e1bf4e848db94ca2584a4c)
Bug 927062 - Remove the 'add call' button when in CDMA call waiting mode r=etienne
Bug 915081 - Hide the end-and-answer button during CDMA call waiting r=etienne

- Removed the end-and-answer button when in CDMA call waiting mode as it
  does not support ending the first call and answering the other one,
  the hold-and-answer button is enlarged to fill up the entire container
  under these conditions
- Added unit-tests covering the changes