Use ProcessEventLocally() added in r64261 (which was probably the one to break
this) to forward event to the window itself instead of ProcessEvent() in
wxScrollHelperEvtHandler::ProcessEvent() implementation. Calling ProcessEvent()
didn't work any more in a case when another event handler was pushed on a
wxScrolledWindow: in this case the EVT_SIZE and EVT_PAINT handlers defined in
the window itself were not called at all any more.
Add a unit test checking for the even more tortuous than usual event
processing path in this particular case.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64358 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775