Fix for 5393156

. Fix for the above.
. Make instances of Space invisible by default.
. Correctly accomodate parental constraints when row/col order is undefined.

This fix allows GridLayout to accomodate simple dependencies between
its axes. In the example given in bug 5393156, the presence of a
multi-line TextView means that GridLayout can only compute its height
after it has computed its width. This fix adds a second measurement pass
to GridLayout that passes infomation betwen the axes, using the GridLayout's
orientation property to indicate which axis should be examined first.

Change-Id: I90761c6fcfe8edc7ef6d9a89076fd5cda3adc0a4