Mark Intl.NumberFormat support partial in Safari

Code examination https://trac.webkit.org/changeset/266031/webkit
indicates that support for compactDisplay, currencySign, notation,
signDisplay, unit, unitDisplay, currencyDisplay: 'narrowSymbol', and
style: 'unit'" wasn’t added until 2020-08-22 — and didn’t make it into
Safari 14 (confirmed by testing), which was released 2020-09-16.

Fixes mdn#9319

javascript/builtins/intl/NumberFormat.json

@@ -36,10 +36,14 @@
                 "version_added": "14"
               },
               "safari": {
-                "version_added": "10"
+                "version_added": "10",
+                "partial_implementation": true,
+                "notes": "Doesn't support <code>compactDisplay</code>, <code>currencySign</code>, <code>notation</code>, <code>signDisplay</code>, <code>unit</code>, <code>unitDisplay</code>, <code>currencyDisplay: 'narrowSymbol'</code>, and <code>style: 'unit'</code>."
               },
               "safari_ios": {
-                "version_added": "10"
+                "version_added": "10",
+                "partial_implementation": true,
+                "notes": "Doesn't support <code>compactDisplay</code>, <code>currencySign</code>, <code>notation</code>, <code>signDisplay</code>, <code>unit</code>, <code>unitDisplay</code>, <code>currencyDisplay: 'narrowSymbol'</code>, and <code>style: 'unit'</code>."
               },
               "samsunginternet_android": {
                 "version_added": "1.5"