fix(deferObservable): accepts factory returns promise

[kwonoj]

Description:

I came to notice PR #1479 becomes redundant by issue #1483 filed after, allowing promise returned by factory function. I have closed #1479 and create this one instead to reflect those.

• factory function now can return either Observable or Promise
• deferObservable internally utilizes subscribeToResult
• as suggested in test(deferObservable): add type definition test #1479, no longer include duplicated type definition test but test case reflects definition usecases

Related issue (if exists):

relates to #1483

** Notes **

Not sure if this change's intended direction in #1483. /cc @trxcllnt to ask review if this change makes sense.

[coveralls]

Coverage increased (+0.006%) to 95.987% when pulling bfe58a1 on kwonoj:type-defer into 91d019c on ReactiveX:master.

[coveralls]

Coverage increased (+0.006%) to 95.987% when pulling cf53d29 on kwonoj:type-defer into 91d019c on ReactiveX:master.

[kwonoj]

Merged with 0cb44e1 .

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.