Calculate and set image intrinsic-size

[Munter]

https://googlechrome.github.io/samples/intrinsic-size/index.html
https://codepen.io/eeeps/pen/qLKwEZ
https://twitter.com/css/status/1085277957873115141?s=19

[papandreou]

This is a really interesting spec!

Since the unit is CSS pixels, it seems like we can't just set intrinsicsize to the width and height of the image without knowing the intended dpr, too? Should we then infer that from whether there's 2x etc. in the file name of the image?

It looks like the presence of a srcset attribute will make this a bit complicated if the images in the set have different aspect ratios. But maybe we should just emit a warning in that case.

[Munter]

As I understand intrinsicsize it's all about the ratio of the image. So in that sense it probably doesn't matter much which srcset version we would choose as the basis. Unless the ratios are different of course

[papandreou]

Hmm, right. I got confused about the scope of intrinsicsize because of "The sizes are in CSS Pixels" here: https://github.com/ojanvafai/intrinsicsize-attribute