Created attachment 226856 [details] test that uses testharness.js When a named flow has no region chain associated, its contents are not visually formatted. So various CSSOM-View attributes and methods should return zero or null for content in this state. This is not happening aside from the x and y image attributes, which are returning zero in all cases (bug https://bugs.webkit.org/show_bug.cgi?id=130308).
The last test (for getBoundingClientRect) assumes that the object returned is a DOMRect with x and y attributes, which is a fairly new thing. The WebKit test might be better off checking left and top for now
CSS Regions were removed in Bug 174978.