Ship NestedTopLayerSupport

Chromestatus:
https://chromestatus.com/feature/5149353645965312

Spec PRs:
whatwg/html#10116
whatwg/fullscreen#237

I2S:
https://groups.google.com/a/chromium.org/g/blink-dev/c/3vIL56MTgvw/m/W4hcWMblBAAJ

Fixed: 1520938
Change-Id: I04e5f217155658907988ed0a0557944dbffbf6f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5255819
Commit-Queue: Mason Freed <masonf@chromium.org>
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1279321}