Reconcile Element and KeyframeEffect iterationComposite data (#29386)

Test-case: https://wpt.fyi/results/web-animations/interfaces/KeyframeEffect/iterationComposite.html?label=master&label=stable&aligned&q=iterationComposite
Issue: web-platform-dx/web-features#3907
Issue: #18963

Co-authored-by: Patrick Brosset <1152698+captainbrosset@users.noreply.github.com>

Author: ddbeck

api/Element.json

@@ -413,15 +413,15 @@
               "opera": "mirror",
               "opera_android": "mirror",
               "safari": {
-                "version_added": false
+                "version_added": "16.4"
               },
               "safari_ios": "mirror",
               "samsunginternet_android": "mirror",
               "webview_android": "mirror",
               "webview_ios": "mirror"
             },
             "status": {
-              "experimental": true,
+              "experimental": false,
               "standard_track": true,
               "deprecated": false
             }