QScrollerPrivate::setDpiFromWidget() before Qt 5.14 crashes
when the target widget does not intersect a physical screen,
because QDesktopWidget returns screen index `-1` in this case,
which leads to an out-of-range read from QApplication::screens(),
which leads to a segfault when reading from an invalid QScreen* pointer.

This adds a workaround that checks for the `-1` situation,
and then tries to resize PageView temporarily to intersect at least some screen.

BUG: 425188
FIXED-IN: 20.12