Always reserver the space for the private browsing indicator, even if
not in private mode. This allows using the same width for the displayed
tab in both modes. Without this, the X of the tab is not visible in
private mode.
I think it's nice to have this space in both modes to quickly close the
menu, as it's right above the menu button.
Apply a similar hack to the "all tabs" menu, as the appMenu has, so it
gets a proper height and doesn't jump above or below the "all tabs"
button, depending on the keyboard being displayed or not. With this
hack, it stays consistently above the button.
