fixes #6331, Variant::can_convert
fixes #6331, Variant::can_convert

(cherry picked from commit f2af5ab9499b343e72269239cb975dd91875bce9)

pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1,pixelpicosean/my-godot-2.1