Import wpt@21a0d1d6eed448496467dadeec26562da516b745

Using wpt-import in Chromium 6580f3fa.
With Chromium commits locally applied on WPT:
9e3affdd "Ship `referer` header length limitation."
bc7ec548 "MSE: Test addSourceBuffer and changeType relaxed type strictness and allowance for implicit changeType"


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=lukebjerring

No-Export: true
Change-Id: Ibf7b692f6268f0d8e10d22bec49b02b2ffb1f0ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1680694Reviewed-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@{#673332}

third_party/blink/web_tests/external/wpt/interfaces/animation-worklet.idl

@@ -18,7 +18,7 @@ interface StatefulAnimator {
   any state();
 };
 
-[ Exposed=AnimationWorklet, Global=AnimationWorklet ]
+[ Exposed=(AnimationWorklet, Worklet), Global=AnimationWorklet ]
 interface AnimationWorkletGlobalScope : WorkletGlobalScope {
     void registerAnimator(DOMString name, AnimatorInstanceConstructor animatorCtor);
 };