- Let's just have one header definining export- and visibility-
macros for Calamares. They are still selected based on the
export flags (*_PRO), just defined in one header instead of two.
- These methods are used for multi-page view-steps, which are rare.
For all the others, just drop the empty implementation and defer
to the base class.
it is no longer maintained upstream
this change is tested with QtWebEngine 5.6.0, it builds and runs
displays the webview page correctly, clicking next however does not refresh that new page completely