Bug with reverting prefab with string property.

[Krzysztof Kansy]

Apparently there is a bug when reverting prefab with string field. Steps to reproduce:

1. Create child and parent prefabs, parent child to prefab.
2. Create script with a public (or in our case private serialized) string field.
3. Attach the script to the child, fill in the string field in inspector with some text.
4. Revert the child, so that the child under parent will be updated with new component.
5. In result, child under parent will have the new component, but the string field will be uninitialized.

[Devon Klompmaker]

Fixed in v1.8f5