Remove duplicated GetTextPeer() definitions from derived classes.

GetTextPeer() may be implemented directly in wxTextEntry under OS X, there is
no need to define it (identically) in wxTextCtrl and wxComboBox.

Also just call this method instead of duplicating its code in wxOSX
wxTextCtrl.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63878 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/textctrl_osx.cpp

@@ -137,11 +137,6 @@ bool wxTextCtrl::Create( wxWindow *parent,
     return true;
 }
 
-wxTextWidgetImpl* wxTextCtrl::GetTextPeer() const
-{
-    return dynamic_cast<wxTextWidgetImpl*> (m_peer);
-}
-
 void wxTextCtrl::MacSuperChangedPosition()
 {
     wxWindow::MacSuperChangedPosition() ;