Promote the current value in any list of predictions, and add it if
there are none.
function() {
        var conversion = this.parse('');
        if (lastSetting) {
            var current = lastSetting.get();
            if (conversion.predictions.length === 0) {
                conversion.predictions.push(current);
            }
            else {
                // Remove current from predictions
                var removed = false;
                while (true) {
                    var index = conversion.predictions.indexOf(current);
                    if (index === -1) {
                        break;
                    }
                    conversion.predictions.splice(index, 1);
                    removed = true;
                }
                // If the current value wasn't something we would predict, leave it
                if (removed) {
                    conversion.predictions.push(current);
                }
            }
        }
        return conversion;
    }