Add missing CSS function keys (#3388)

Author: jamesnw

features/draft/spec/css-mixins-1.yml

@@ -2,4 +2,16 @@ name: "@function"
 description: "The `@function` CSS at-rule defines a custom function that takes CSS values or custom properties as arguments, and returns a CSS value. It can be based on conditional logic such as by using the `@media` at-rule."
 spec: https://drafts.csswg.org/css-mixins-1/#function-rule
 group: css
-# No compat keys yet, this feature is planned to ship with Chromium 139
+compat_features:
+  - api.CSSFunctionDeclarations
+  - api.CSSFunctionDeclarations.style
+  - api.CSSFunctionDescriptors
+  - api.CSSFunctionDescriptors.result
+  - api.CSSFunctionRule
+  - api.CSSFunctionRule.getParameters
+  - api.CSSFunctionRule.name
+  - api.CSSFunctionRule.returnType
+  - css.at-rules.function
+  - css.at-rules.function.result
+  - css.types.dashed-function
+  - css.types.type

features/draft/spec/css-mixins-1.yml.dist

@@ -3,4 +3,20 @@
 
 status:
   baseline: false
-  support: {}
+  support:
+    chrome: "139"
+    chrome_android: "139"
+    edge: "139"
+compat_features:
+  - api.CSSFunctionDeclarations
+  - api.CSSFunctionDeclarations.style
+  - api.CSSFunctionDescriptors
+  - api.CSSFunctionDescriptors.result
+  - api.CSSFunctionRule
+  - api.CSSFunctionRule.getParameters
+  - api.CSSFunctionRule.name
+  - api.CSSFunctionRule.returnType
+  - css.at-rules.function
+  - css.at-rules.function.result
+  - css.types.dashed-function
+  - css.types.type