Backport of "subparse: fix pushing WebVTT cue with no newline at the end" into 1.16
requested to merge tpm/gst-plugins-base:backport-mr-232-into-1.16-subparse-fix-webvtt-no-newline-at-the-end into 1.16
Backport of !232 (merged) "subparse: fix pushing WebVTT cue with no newline at the end".
Commits: