When you open image-diff in a new window it defaults to max-width 100%. This feels more natural for looking at large images. Clicking on the image will toggle fitting to the page width or natural size.
Chrome no longer allows dataURIs to be viewed directly in the URL bar ([background](https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/GbVcuwg_QjM%5B101-125%5D)).
Currently clicking on the #image-diff element loads a blank page and gives an error:
> Not allowed to navigate top frame to data URL
This change opens the new window as `about:blank`, creates an image element, and appends that to the page.