Assign transformer_cancel BCD feature to transformstream-transformer-cancel

Author: MattiasBuelens

features/transformstream-transformer-cancel.yml

@@ -2,3 +2,5 @@ name: "TransformStream: transformer.cancel method"
 description: The `cancel` method of a `TransformStream` transformer allows you to clean up resources when the readable side is cancelled or the writable side is aborted.
 spec: https://streams.spec.whatwg.org/#dom-transformer-cancel
 group: streams
+compat_features:
+  - api.TransformStream.TransformStream.transformer_cancel

features/transformstream-transformer-cancel.yml.dist

@@ -4,3 +4,5 @@
 status:
   baseline: false
   support: {}
+compat_features:
+  - api.TransformStream.TransformStream.transformer_cancel