GST_STATE_CHANGE_READY_TO_READY is undefined in gstreamer 1.12.x and needs a version check.
Created attachment 394000 [details] Patch.
Committed r258755: <https://trac.webkit.org/changeset/258755> All reviewed patches have been landed. Closing bug and clearing flags on attachment 394000 [details].
<rdar://problem/60676531>