Add discouraged mutation events (#2518)

Co-authored-by: Daniel D. Beck <[email protected]>

features/mutation-events.yml

@@ -0,0 +1,17 @@
+name: Mutation events
+description: Mutation events like `DOMSubtreeModified`, `DOMNodeInserted`, or `DOMNodeRemoved` fire when DOM changes occur.
+# The latest spec doesn't mention them at all anymore.
+spec: https://w3c.github.io/uievents/
+discouraged:
+  according_to:
+    - https://www.w3.org/TR/2024/WD-uievents-20240906/#legacy-mutationevent-events
+  alternatives:
+    - mutationobserver
+compat_features:
+  - api.MutationEvent
+  - api.MutationEvent.attrChange
+  - api.MutationEvent.attrName
+  - api.MutationEvent.initMutationEvent
+  - api.MutationEvent.newValue
+  - api.MutationEvent.prevValue
+  - api.MutationEvent.relatedNode

features/mutation-events.yml.dist

@@ -0,0 +1,18 @@
+# Generated from: mutation-events.yml
+# Do not edit this file by hand. Edit the source file instead!
+
+status:
+  baseline: false
+  support:
+    firefox: "1"
+    firefox_android: "4"
+    safari: "1"
+    safari_ios: "1"
+compat_features:
+  - api.MutationEvent
+  - api.MutationEvent.attrChange
+  - api.MutationEvent.attrName
+  - api.MutationEvent.initMutationEvent
+  - api.MutationEvent.newValue
+  - api.MutationEvent.prevValue
+  - api.MutationEvent.relatedNode