You spin me right ‘round baby, right ‘round
When you press Shift-R, baby…
Check this out: Go to photos.google.com, click one of your images, and press Shift-R. Boom, super slick, hardware-accelerated 90º rotation—no need to click the pencil icon, go into crop/rotate mode, click a button, and save changes.
Each time you press Shift-R, the image will rotate another 90º. This is a godsend especially if you’re dealing with a bunch of old, mis-rotated images: Just click, Shift-R, right arrow, Shift-R, etc.; rinse, repeat, rock out.