Import wpt@fdc1a89a01a437cce2afa78fad440f68d1d46935

Using wpt-import in Chromium d2478a08.
With Chromium commits locally applied on WPT:
1029b7e9 "SharedWorker: Add WPT for upgrade-insecure-requests"


Note to sheriffs: This CL imports external tests and adds
expectations for those tests; if this CL is large and causes
a few new failures, please fix the failures by adding new
lines to TestExpectations rather than reverting. See:
https://chromium.googlesource.com/chromium/src/+/master/docs/testing/web_platform_tests.md

NOAUTOREVERT=true
TBR=robertma

No-Export: true
Change-Id: I2d1a1e3d9c44188467e9ccc094bf0628b7595c4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2027256Reviewed-by: WPT Autoroller <wpt-autoroller@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: WPT Autoroller <wpt-autoroller@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#736285}

third_party/blink/web_tests/external/wpt/dom/events/webkit-animation-iteration-event.html

@@ -15,6 +15,9 @@
 runAnimationEventTests({
   unprefixedType: 'animationiteration',
   prefixedType: 'webkitAnimationIteration',
-  animationCssStyle: '50ms 2',
+  // Use a long duration to avoid missing the animation due to slow machines,
+  // but set a negative delay so that the iteration boundary happens shortly
+  // after the animation starts.
+  animationCssStyle: '100s -99.9s 2',
 });
 </script>