Tests inheritance of transition-property.

PASS: Box 1 computed transition-property: all, expected: all
PASS: Box 2 computed transition-property: left, expected: left
PASS: Box 3 computed transition-property: left, expected: left
PASS: Box 4 computed transition-property: left, expected: left
PASS: Box 5 computed transition-property: left, expected: left
PASS: Box 6 computed transition-property: all, expected: all