Some mobile browsers creating (new, non-identifiable) exif data on export to jpeg

[everestpipkin]

On iOS devices and in Safari, canvas.toBlob() function creates an image with new generated exif data describing its resolution, colorspace, compression, etc. It is nothing from the original photo, but it would display information on reload into the tool and might lead some people to believe the data had not been removed. We were originally using toDataUrl() but switched to toBlob() for a big performance boost. (Thank you @SaFrMo for the tip on this exif data behavior).

This is currently fixed by changing export filetype to png instead of jpeg, but pngs makes a much larger filesize and this should probably not be the long-term solution.