The properties `repeatx` and `repeaty` are missing when exporting json map. #3307

Describe the bug The properties repeatx and repeaty are missing when exporting a json map. To be clear: These properties are fine when doing a regular save, but when

To Reproduce Steps to reproduce the behavior:

1. Create a map with a image layer.
2. Check repeatx and repeaty.
3. Save As... .json, and notice the properties repeatx and repeaty are there.
4. Export As... .json, and notice the properties repeatx and repeaty are missing.

Expected behavior I expect these properties to exist when exporting a json.

Media

Specifications:

• OS: Manjaro Linux
• Tiled Version: 1.8.2