QWebEnginePage::setBackgroundColor doesn't work properly

Related to QTBUG-67434

Using simplebrowser and adding setBackgroundColor(Qt::red); in the constructor of WebPage.

Pages without a background do show a red background if and only if they are the first URL loaded in a tab.

Examples:

1. Create a new tab
2. Load http://perdu.com/ => red background
3. Load file:///dev/null => white background
4. Load http://perdu.com => white background

1. Create a new tab
2. Load file:///dev/null => red background
3. Load http://perdu.com => white background
4. Load file:///dev/null => white background