Bug 977056 - [Dialer] Visual discrepancies: Call ended view under conference call participants list

It is currently being used here: https://github.com/gtorodelvalle/gaia/blob/callscreen-bug-977056-participant-leaving-conference/apps/callscreen/js/handled_call.js#L20 We only clone the call node in the case of an unmerged call when the call node is in the participant list overlay before it is inserted into the main call screen to keep it there before the overlay is automatically closed.