animations: Don't apply animation delay to every iteration

The delay should only be applied to the animation before the first
iteration.

tests/wpt/mozilla/meta/MANIFEST.json

@@ -12866,6 +12866,13 @@
    },
    "css": {
     "animations": {
+     "animation-delay.html": [
+      "0d2053a9134d8ff0ade7b5dc37ecfce305557c44",
+      [
+       null,
+       {}
+      ]
+     ],
      "animation-events.html": [
       "0975aa64ec47ca4b4c8fc1e0a40414a51719ad67",
       [
@@ -12876,7 +12883,7 @@
       ]
      ],
      "animation-fill-mode.html": [
-      "4cfaab9fbce0adccd83f592935e63fa8ff58a1cf",
+      "9602ec9f0e0eb1f6efcc2e7bd95181ef65339bae",
       [
        null,
        {}