Add support for dragging a shader to user exported material property

Author: jsjtxietian

editor/editor_resource_picker.cpp

@@ -618,9 +618,9 @@ void EditorResourcePicker::_ensure_allowed_types() const {
 		const String base = allowed_types[i].strip_edges();
 		if (base == "BaseMaterial3D") {
 			allowed_types_with_convert.insert("Texture2D");
-		} else if (base == "ShaderMaterial") {
+		} else if (ClassDB::is_parent_class("ShaderMaterial", base)) {
 			allowed_types_with_convert.insert("Shader");
-		} else if (base == "Texture2D") {
+		} else if (ClassDB::is_parent_class("ImageTexture", base)) {
 			allowed_types_with_convert.insert("Image");
 		}
 	}