I wasn't the one who posted the ad, but I googled "Roller Skating doll
ad (Sybil Jason) and came up with these results including several
pictures for the doll. Hope this
helps.https://www.google.com/search?q=Roller+Skating+doll+ad+(Sybil+Jason&sxsrf=...
Does it look like it is handmade? There is a completed auction for a
pattern for a Shirley Temple doll dress that looks a lot like your
dress. In the lower right.
https://www.ebay.com/itm/Vtg-30s-Shirley-Temple-HEIDI-Doll-Clothes-Dress-Coat-Hat-Patte...
Is this her?
https://www.ebay.com/itm/Disney-Its-A-Small-World-ENGLAND-Singing-16-Doll-Animator-Collection-Retired/233240068480?hash=item364e310180:g:s2kAAOSw4h1c7Fw6