[MOVED FROM BAD 099/134] vp8dec: use is_alt_data option to prevent timestamp collisions
altref/invisible frames usually stored in container with same timestamp as
dependet frame. This make basevideodecoder to update timestamp for dependet
frame and couse TS colision on next frame:
^- here is altref
time : 1 2 3 4 5 6 7 8 9
webm ts : 1 3 5 5 7 9
vp8dec ts: 1 3 7 7 9
Fix bug: https://bugzilla.gnome.org/show_bug.cgi?id=655245
Signed-off-by: Oleksij Rempel (Alexey Fisher) <bug-track@fisher-privat.net>