Issue with responsive images and DPR on mobile

[alexpainter]

When responsive images are used with srcset, it looks as though images that are the right size are highlighted in blue (too small) and images that are too big are highlighted in green (OK) when emulating a mobile device with a high DPR in Devtools. I think this might be to do with using naturalWidth for the image element, rather than looking to naturalWidth of currentSrc - demo page here: https://www.alexrp.co.uk/nl/testresponse.html

[tabanliviu]

Thanks a lot of the bug report. Will try and get this sorted for the 1.6.0 release