Fixed a problem where ArrayHandle would cause a crash if you tried to
get the control portal on an uninitialized array (it was supposed to
throw an exception).

Also changed some methods in ArrayHandle so that they work resonably
without error when used with an uninitialized array. Specifically, the
aforementioned behavior was changed to "allocate" an array of size 0
(that is, call Allocate(0) on the storage object) to return an empty
array portal rather than throw an error. Although this use of
ArrayHandle can be considered erroneous, it is convenient the get an
empty array portal when dealing with a potentially unallocated array
rather than create a special condition.