Timeline essays are loading full size original images

[MegaKeegMan]

Timeline essays can render images from media entities on referenced artifacts, and they can render background images directly from the timeline item background field. Both of these are rendering full size images, without doing any image style processing.

Ideally, it would be great to load these responsively, but a solid first step would be using an image style at all, which is where we will start for this, mostly to be respectful of the user's bandwidth.

[MegaKeegMan]

The above commit applies an image style to images from artifact media entities. We still need image styles for background images.