An as-character image is now a line box in getLineRects, so a paragraph of
stacked images breaks between them instead of overflowing the page. Only a
floated image keeps its paragraph atomic, and the leaf's height reaches down
to the lowest float — a float hangs out of the paragraph's box, so
offsetHeight alone let the image walk off the page foot. prevPlacementsKey
damps the ping-pong that overhang causes between two layouts.
Steffen Becker
e9e543fe8c