We were just there in February and I too didn't see any kid-sized toilets.
And one other word of warning, ALL of the WDW toilets have the automatic sensors so it's hands free flushing. Cool idea, but I learned quickly that my DD (almost 4) is TERRIFIED of it. Because her butt doesn't entirely cover the seat, it's easy for the sensor to detect that the person is finished. I had to keep my finger FIRMLY on the sensor while she went.....one poster on this site suggested taking along a post-it note and just stick it to the wall. I'll have to remember that for next time!
If you don't think that your child can handle a full sized toilet, check out Babie's R Us. When my DD was going through potty training and didn't want to go in a public restroom, we bought this little fold-up potty seat. It has these disposable "liners" and it just sits inside the seat then you throw away the liner. It's a pretty clean setup and easy to do. You can just take it into the stall with you and have your kid go. It was about $15 I think. We kept ours in the van on road trips in case we ever have to pull over.