reverted Julian's r44600, it broke help window behavior so that it prevented apps from closing

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52472 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/html/helpfrm.cpp

@@ -55,7 +55,6 @@
 #include "wx/fontenum.h"
 #include "wx/artprov.h"
 #include "wx/spinctrl.h"
-#include "wx/app.h"
 
 IMPLEMENT_DYNAMIC_CLASS(wxHtmlHelpFrame, wxFrame)
 
@@ -246,11 +245,4 @@ void wxHtmlHelpFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
 }
 #endif
 
-// we don't want to prevent the app from closing just because a help window
-// remains opened
-bool wxHtmlHelpFrame::ShouldPreventAppExit() const
-{
-    return (wx_const_cast(wxHtmlHelpFrame*, this) == wxTheApp->GetTopWindow());
-}
-
 #endif // wxUSE_WXHTML_HELP