It was only testing the default configuration, where overlay scrolling
is on and both scrollbars use POLICY_AUTOMATIC. We should also test the
other 3 configurations that are available by including non-overlay
scrollbars and/or those that use POLICY_ALWAYS.
https://bugzilla.gnome.org/show_bug.cgi?id=778853
It was only testing the default configuration where overlay-scrolling is
TRUE and the policy is POLICY_AUTOMATIC. We should also test FALSE and
POLICY_ALWAYS. This commit adds those tests and makes the !overlay &&
POLICY_ALWAYS case pass by excluding the size of the relevant scrollbar,
as we are only interested in whether the content size is as requested.
https://bugzilla.gnome.org/show_bug.cgi?id=778853
The maximum content size does not increase the minimum request
but only ensures that both minimum and natural requests do not
exceed the maximum setting.
