Bug 1072143 - [LockScreen] Add |transferOut| method in LockScreenStateMa...

...nager
Never call promise within another promise; chain them instead. This should be rewritten to:

    this.previousState.transferOut()
    .then(() => { this.previousState = state; })
    .then(state.transferTo.bind(this, currentStates))
    .then(this.onTransferringDone.bind(this), this.onTransferringError.bind(this));