Get rid of all the event boxes in this test. Event boxes need GDK
windows which cost a lot of performance when running the test and they
clip the label output.
Getting rid of the clipping also shows 2 bugs in this test that weren't
visible before. Those will be fixed in a followup patch.
When tests are larger than the screen size and no compositing is
enabled, the window will be clipped to the screen size and all areas
outside of the screen have undefined contents.
To avoid this, we can use an offscreen window.
Checks that the size requests for labels are as they should be for
required and natural size given various combinations of wrap, ellipsize,
width-chars and max-width-chars.
See
http://mail.gnome.org/archives/gtk-devel-list/2011-April/msg00036.html
for the discussion spawning this test.
