improve backwards compatibility of OSIS post-CR6887286

If we add a call imageComplete() with SINGLFAMEDONE before the call with STATICIMAGEDONE, we can increase backwards compatibility with end user code that depends on the pre-CR6887286 behavior (when only SINGLEFRAMEDONE was passed).

In CR6887286, we changed OSIS to pass STATICIMAGEDONE instead of SINGLEFRAMEDONE when it calls imageComplete(). This introduced a potential compatibility risk as some 3rd party / end user code may depend on the previous behavior (i.e. wait indefinitely for SINGLEFRAMEDONE to be passed). If we call imageComplete() twice, once with the value we passed before CR6887286, SINGLEFRAMEDONE, and THEN with the new value, STATICIMAGEDONE, we can ensure that any pre-existing code that depends on SINGLEFRAMEDONE will continue to work. the GIF implementation already can exhibit this behavior, so it should be safe for OSIS to also do this. Calling SINGLEFRAMEDONE and then immediatly calling STATICIMAGEDONE is also not a violation of the JavaDoc.