Update Image Layer Style to add a mask - do not render "Nodata"

[mattkramer]

Hello! I was curious if it was possible to add a "Mask" to images that are layers in a web map. In ArcGIS Pro, this is an option in the symbology of an image layer. I have been unable to find a similar property in the web map. 

Ultimately, I am looking for a way to stop the black space in the below screenshot from rendering within a web map.