DatePickers not shown when loaded from AdaptiveLayout

[lduboeuf]

DatePickers are not shown when loaded from an AdaptiveLayout.
A work around is to set property asynchronous to false to AdaptiveLayout

Step to reproduce:

// DatePickerPage.qml
import QtQuick 2.0
import Ubuntu.Components 1.3
import Ubuntu.Components.Pickers 1.3

Page {
    id: failPage
    DatePicker {
    }
}

// DatePickerFail.qml
import QtQuick 2.4
import Ubuntu.Components 1.3


MainView {
    id: root

    width: units.gu(45)
    height: units.gu(75)

    AdaptivePageLayout {
        id: layout
        anchors.fill: parent
        primaryPageSource: Qt.resolvedUrl("DatePickerPage.qml")
    }
}

Run qmlscene DatePickerFail.qml, DatePicker is not shown