Comment 57 for bug 327863

On further investigation I really don't think this is going to work. As far as I can tell, what's setting the scrollbar size to 0 is the call to nsBoxFrame::LayoutChildAt from LayoutAndInvalidate (static function in nsGfxScrollFrame.cpp) from nsGfxScrollFrameInner::LayoutScrollbars ... and lying to that function about the amount of space available to the scrollbar just trips *different* pres shell assertions ("reflow roots must not have visible overflow").