Easily reproducible in Chromium with --enable-threaded-compositing flag. Resize any window, and the contents don't refresh or resize.
I wonder what broke this after http://code.google.com/p/chromium/issues/detail?id=103776.
It probably broke because we didn't have a test for it (cue Beyonce).
Antoine, can you take a look?
Problem is in chrome land. http://codereview.chromium.org/8912002/ fixes it.