[tools]: Crow updates to 'infix://=' ~ fixed usage (does not return values, uses assign to modify in-place) ~ added null guard
[tools]: Crow updates to 'infix://='
~ fixed usage (does not return values, uses assign to modify in-place)
~ added null guard

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@17352 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot