fixed parsing bug if EXTINF tag is not followed by the segment URI

For example:

#EXTM3U
#EXT-X-TARGETDURATION:3
#EXT-X-MEDIA-SEQUENCE:461423582
#EXT-X-VERSION:3
#EXTINF:3,
#EXT-X-KEY:METHOD=NONE
#EXT-X-PROGRAM-DATE-TIME:2013-11-12T15:39:08Z
20131112T091349-04-461423582.ts
#EXTINF:3,
#EXT-X-KEY:METHOD=NONE
#EXT-X-PROGRAM-DATE-TIME:2013-11-12T15:39:11Z
20131112T091349-04-461423583.ts
#EXTINF:3,
#EXT-X-KEY:METHOD=NONE
#EXT-X-PROGRAM-DATE-TIME:2013-11-12T15:39:14Z
20131112T091349-04-461423584.ts

will parse '#EXT-X-KEY:METHOD=NONE' as the URI.