Fix cache element invalidation bug.
Fix cache element invalidation bug.

Although we only want to cache compatible full elements, invalidation
needs to occur even when an element is given that has a superextent of
the vertex to be invalidate. This typically happens when invalidation of
an ancestor compute X propagates to a descendant compute Y where Y's
scope includes subextents of the extents of X's scope.

marktsuchida/NDMake