Enable the unprefixed Fullscreen API behind experimental flag

After https://chromium-review.googlesource.com/521162 the API is quite
closely aligned with the standard, although the rendering bits still are
not.

Enabling it will make it easier to test, and might shake out compat
problems in the wild earlier.

Bug: 383813
Change-Id: I0c9add3bdc77f689deeafb207022e5c9fea1e3bd
Reviewed-on: https://chromium-review.googlesource.com/544303
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#481669}
1 file changed