Add wxTopLevelWindow::SetRepresentedFilename().

This currently is only implemented under OS X and sets the proxy icon there
but could be implemented to do something useful under the other platforms too
in the future.

Closes #13797.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70295 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/toplevel_osx.cpp

@@ -213,3 +213,8 @@ bool wxTopLevelWindowMac::OSXIsModified() const
 {
     return m_nowpeer->IsModified();
 }
+
+void wxTopLevelWindowMac::SetRepresentedFilename(const wxString& filename)
+{
+    m_nowpeer->SetRepresentedFilename(filename);
+}