[text tracks] take into account the video element parent container s…
Created by: jeffcunat
Fix issue #2241 (closed) This PR takes into account the fact that the parent container of the video element can have a different size than the video element itself. It also takes into account the relative positioning of the video element inside its parent (ex: vertically centered video element in fullscreen mode)
@Gontran-Molotov : could you check if it is OK for your use cases ?