anchor-size(): make consistent with margin, inset data (#29626)

This aligns `css.types.anchor-size.inset_margin` with
`css.properties.inset.anchor-size`, `css.properties.margin.anchor-size`,
and many others.

I think this was an omission in #28649.

Author: ddbeck

css/types/anchor-size.json

@@ -38,7 +38,7 @@
         },
         "inset_margin": {
           "__compat": {
-            "description": "Valid in inset and margin property values.",
+            "description": "Valid in `inset` and `margin` property values.",
             "spec_url": "https://www.w3.org/TR/css-logical-1/#inset-properties,https://www.w3.org/TR/css-box-4/#margin-properties",
             "tags": [
               "web-features:anchor-positioning"
@@ -50,8 +50,7 @@
               "chrome_android": "mirror",
               "edge": "mirror",
               "firefox": {
-                "version_added": "preview",
-                "impl_url": "https://bugzil.la/1972610"
+                "version_added": "147"
               },
               "firefox_android": "mirror",
               "oculus": "mirror",