This is a beta release, only install it if you know what that means
Allow html-entities inside href="" as valid URL
Unknown image dimension magics
2 new Advanced options:
Fix unknown image sizes (on by default)
Utilize visitors's browsers to check image sizes where server failed (off by default)
This option from our own testing is able to find image dimensions for ~5% of the ones where server failed (most other seem to be expired domains/images)
new endpoint at /ampimgsize where admins can see short summary of how many image sizes that have been found so far.
If you want to see how much impact this feature has on AMP page generation you can add &time=1 to the AMP url and it will print out a debug line with how many image dimensions where fixed in how long time.
spoiler alert: it is minimal, most we have seen on our own forum is e.g. "5 images replaced in 0.3ms"
note: If no image dimensions were fixed for the page you test on, it won't print out anything.
How the image dimension magic works:
The first time an image with unknown dimensions is encountered the AMP page will render with the unknown-image class, and the URL will be put in a queue to be checked by the server in a cronjob.
Once image dimensions are known, it will be inserted with correct width="" and height="" attributes which the AMP spec wants..