[:is/:where] Make is-where-error-recovery.html non-tentative

It's now in the spec, so it should be fair to remove the .tentative
tag.

Bug: 568705
Change-Id: I527632906e49f6d4f9909c75750acbc6e5e91c82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2479364
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Reviewed-by: Emilio Cobos Álvarez <emilio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818401}

third_party/blink/web_tests/external/wpt/css/selectors/is-where-error-recovery.tentative.html → third_party/blink/web_tests/external/wpt/css/selectors/is-where-error-recovery.html

@@ -4,6 +4,7 @@
 <link rel="help" href="https://github.com/w3c/csswg-drafts/issues/3676">
 <link rel="help" href="https://drafts.csswg.org/selectors-4/#matches">
 <link rel="help" href="https://drafts.csswg.org/selectors-4/#zero-matches">
+<link rel="help" href="https://drafts.csswg.org/selectors-4/#typedef-forgiving-selector-list">
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <style id="test-sheet">