Is there any possible way to get these hearts as Adult Link?
I'm playing this game and I didn't get the hearts outside Zora's domain before becoming Adult Link. 
Yes, collecting this Piece of Heart is possible as an adult, and very simple too. All you need is the Hover Boots found in the Shadow Temple of Kakariko.
However, by the time you can enter the Shadow Temple, you'll already have been granted the ability to turn back into a child. This means you could just grab a Cucco and get the piece before completing either the Bottom of the Well, or finding the Hover Boots in the Shadow Temple.
The choice is yours.