CustomIndexedGetter allows to customize binding for object's indexed getter. Already exists CustomNamedSetter, CustomIndexedSetter and CustomNamedGetter, but CustomIndexedGetter is missing. This is needed by Gamepad API to allow gamepad list to customize indexed getter to contain holes. Eg: [{"gamepad1", undefined, "gamepad3", undefined, ... , undefined].
No longer applies after: https://webkit.org/b/133586
This is addressed in 133586. *** This bug has been marked as a duplicate of bug 133586 ***