[DevTools] Deflake and re-enable dom-getFrameOwner.js test.

The test was racy wrt. the target creation and catching the event, but
it was also relying on the `nodeId` return value of `DOM.getFrameOwner`,
which is not guaranteed to be there.

Fixed: chromium:1367372, chromium:1179857
Change-Id: I6f4b3f237cb175acfceb7facbb96c24707ce41d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4958774
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Ergün Erdoğmuş <ergunsh@chromium.org>
Reviewed-by: Ergün Erdoğmuş <ergunsh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1212668}