[Reg 5.7.1 -> 5.8] Setting a QDockWidget with a QQuickWidget in it to floating crashes the renderer

#include <QApplication>
#include <QDockWidget>
#include <QQuickWidget>
#include <QMainWindow>
#include <QTimer>

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0) :
        QMainWindow(parent)
    {
        QDockWidget *dock = new QDockWidget(this);
        QQuickWidget *quick = new QQuickWidget(dock);
        quick->setSource(QUrl("qrc:/main.qml"));

        QTimer::singleShot(1000, dock, [dock]() { dock->setFloating(true); });
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

#include <main.moc>

import QtQuick 2.0

Rectangle {
    width: 500
    height: 500

    color: "green"

    MouseArea {
        anchors.fill: parent
        onClicked: console.log("clicked")
    }
}