Move GTK3 wxNO_BORDER handling to wxControl

So wxNO_BORDER works with other controls, such as wxBitmapButton.
Also use GTK prefix on ApplyCssStyle(), and add an overload that
creates the GtkCssProvider.

src/gtk/textctrl.cpp

@@ -32,7 +32,6 @@
 #include <gtk/gtk.h>
 #include "wx/gtk/private.h"
 #include "wx/gtk/private/gtk2-compat.h"
-#include "wx/gtk/private/object.h"
 
 // ----------------------------------------------------------------------------
 // helpers
@@ -728,18 +727,10 @@ bool wxTextCtrl::Create( wxWindow *parent,
         // new, empty control, see https://trac.wxwidgets.org/ticket/11409
         gtk_entry_get_text((GtkEntry*)m_text);
 
+#ifndef __WXGTK3__
         if (style & wxNO_BORDER)
-        {
-#ifdef __WXGTK3__
-            // this is sort of a workaround for when the builtin theme
-            // won't remove the frame by itself -- see
-            // https://bugzilla.gnome.org/show_bug.cgi?id=789732#c1
-            wxGtkObject<GtkCssProvider> provider(gtk_css_provider_new());
-            ApplyCssStyle(provider, "* { border: none; border-radius: 0; padding: 0 }");
-#else
             gtk_entry_set_has_frame((GtkEntry*)m_text, FALSE);
 #endif
-        }
 
     }
     g_object_ref(m_widget);