Clean up dead code
Clean up dead code

After some recent changes, set_cursor_impl was no longer used.

google/xi-editor,modelorganism/xi-editor,modelorganism/xi-editor,google/xi-editor,google/xi-editor,modelorganism/xi-editor,fuchsia-mirror/third_party-xi-editor,fuchsia-mirror/third_party-xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,fuchsia-mirror/third_party-xi-editor