QQuickWidget shows black content when running in release mode

1. Run the demo attached to QTBUG-40743 in debug mode
(qmake.exe qnswindow.pro -r -spec win32-msvc2010 "CONFIG+=declarative_debug" "CONFIG+=qml_debug")
2. Click "File->Create quick view". Notice that the window that pops up is displayed correctly
3. Run the demo in release mode
(qmake.exe qnswindow.pro -r -spec win32-msvc2010 "CONFIG+=release")
4. Click "File->Create quick view". Notice that a black window pops up

This issue happens on 5.3.1 (ANGLE), after applying QQuickWidget patches up until https://codereview.qt-project.org/#/c/92764/