How to compile custom icons into my visual

Hello!

I am building a visual with an "fancytree" treeview and this view needs a .gif file inside the .css file, can i compile my .gif so it stays with inside my visual (and not on an 3rd party webserver) and if yes how can i reach/get it? 

i tried adding it into the tsconfig.json but i am getting a extension error : 

TYPESCRIPT   File 'C:/Work/PowerBI/jqueryTest/.tmp/precompile/style/icons.gif' has unsupported extension. The only supported extensions are '.ts', '.tsx', '.d.ts', '.js', '.jsx'.

Greetings.