The shadow on the right side of the table doesn't show up when the page doesn't fit in a browser window. Resize the window in the url to less then 500x500px. You will notice that you can't see the box-shadow on the right side of the box.
Forgot to add box-shadow to RenderTable overflow.
Did you forget RenderFlexibleBox too?
(In reply to comment #2) > Did you forget RenderFlexibleBox too? > No! :-)
Created attachment 14738 [details] Add box-shadow to table visual overflow
Comment on attachment 14738 [details] Add box-shadow to table visual overflow r=me
Landed in r21807.