Use the opener document execution context during media player creation

This change fixes a bug where the browser would crash when a video
element is moved into a Picture in Picture window and a new player is
created for it.

The new player would retrieve a media inspector context that is
associated with the PiP window. Once the PiP window is closed the
media inspector context becomes a candidate for garbage collection.

The crash takes place once the media inspector context is garbage
collected and a subsequent media log generated.

This change fixes the issue by using the media element opener document
execution context, when needed, during player creation.

A side effect is that when the opener document execution context is
used, media logs will not be visible from the PiP DevTools panel,
however this aligns with other decisions to delegate responsibility to
the opener (e.g. https://crbug.com/40866464).

Bug: 377728959
Change-Id: I70f87c480189fdf665ff9bebca806c7608316118
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6038314
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Benjamin Keen <bkeen@google.com>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1391394}