Testing Iteration Protocol (Sub-Phase 5.1)
Array it.next().value (1): 1
Array it.next().value (2): 2
Array it.next().value (3): 3
Array it.next().done: true
String it.next().value (X): X
String it.next().value (Y): Y
String it.next().value (Z): Z
String it.next().done: true
Custom iterable for...of: 10 20 30 
Array for...of: 10 20 30