When a flow contains an image and there is a region chain consuming the flow, if the image does not fit in a region and overflows in another, the image element is visually split between the two regions (see attached file in WebKit nightly build). This also affects other inline blocks (e.g. a <div> with display: inline;) but not text.
Created attachment 132031 [details] Reduced testcase
Created attachment 132032 [details] Reduced testcase Cleaned up the test-case.
Still repros on today's nightly (r151543)
This doesn't seem to be limited to images only, but to all replaced elements (images, videos, iframes, canvases)
Fixed with the overflow implementation. Closing.