Bug 1044224 - [Messages][Tests] Generate assets on the fly instead of loading it with XHR. Generating assets using canvas. r=julien

so, if you put these assets in /js, they'll be packaged within the app...

It's not an issue when the asset is small, but here the bmp file is quite big.
I think we have a way ignore a part of the app files but I'm not sure, maybe needinfo :yurenju on the bug.