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

include/wx/osx/textctrl.h

@@ -26,9 +26,6 @@
 #include "wx/control.h"
 #include "wx/textctrl.h"
 
-// forward decl for wxListWidgetImpl implementation type.
-class WXDLLIMPEXP_FWD_CORE wxTextWidgetImpl;
-
 class WXDLLIMPEXP_CORE wxTextCtrl: public wxTextCtrlBase
 {
   DECLARE_DYNAMIC_CLASS(wxTextCtrl)
@@ -142,7 +139,6 @@ public:
     virtual void MacSuperChangedPosition();
     virtual void MacCheckSpelling(bool check);
 
-    virtual wxTextWidgetImpl * GetTextPeer() const;
 protected:
     // common part of all ctors
     void Init();