Reland ios accessibility scrolling support (#26860)

https://dart.googlesource.com/external/github.com/flutter/engine/+/7aa61d664fc3234265a818646ecf22230535880f
diff --git a/commits.json b/commits.json
index 19f727b..cd1d189 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "external/github.com/flutter/engine":"99b752ed2c8f87bb1d13d89a7cee3fb9caa3b1f2",
+  "external/github.com/flutter/engine":"7aa61d664fc3234265a818646ecf22230535880f",
   "external/github.com/flutter/flutter":"9c0bd18c40f1509e16079142c441bfee025da976",
   "sdk":"c54ce0b969e5b3a7449f20e9ddf193e96556c519"
 }
\ No newline at end of file