Add Platform::qobjectAsView()

to be removed once we port away from Qt, but needed for now to
support QtQuick

src/qtquick/Platform_qtquick.h

@@ -24,6 +24,7 @@ public:
     ~Platform_qtquick() override;
     const char *name() const override;
     std::shared_ptr<ViewWrapper> focusedView() const override;
+    std::shared_ptr<ViewWrapper> qobjectAsView(QObject *) const override;
 
 private:
     void init();