Before this change, the activeElement used to be the body and not
multiview. Then, the EventListener wasn't triggering.

Bug: v8:7327
Change-Id: I9782159ffd510c9a7afd83695f20ede9e774ac20
Notry: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1868624
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64422}