Safari iOS does not support initial-letter with decimals (#27941)

Update Safari iOS support to add a note, and make it partially implemented


Co-authored-by: Claas Augner <[email protected]>

Author: Bashamega

css/properties/initial-letter.json

@@ -27,7 +27,15 @@
               "version_added": "9",
               "notes": "See [bug 229090](https://webkit.org/b/229090) for the unprefixed property."
             },
-            "safari_ios": "mirror",
+            "safari_ios": {
+              "prefix": "-webkit-",
+              "version_added": "9",
+              "partial_implementation": true,
+              "notes": [
+                "See [bug 229090](https://webkit.org/b/229090) for the unprefixed property.",
+                "Does not support decimal values. See [bug 296785](https://webkit.org/b/296785)."
+              ]
+            },
             "samsunginternet_android": "mirror",
             "webview_android": "mirror",
             "webview_ios": "mirror"