content-visibility: Rename tentnative test to non-tentative.

This patch renames a wpt, since the fact that the property is
no longer animatable has been approved by csswg.

R=chrishtr@chromium.org

Change-Id: Ib6e937d6df223755f67c3698a0cb09aba7775fa1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2542368
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827957}
diff --git a/css/css-contain/content-visibility/content-visibility-077.tentative.html b/css/css-contain/content-visibility/content-visibility-077.html
similarity index 100%
rename from css/css-contain/content-visibility/content-visibility-077.tentative.html
rename to css/css-contain/content-visibility/content-visibility-077.html