[null-safety] remove more usage of mockito from the framework tests (#62936)

https://dart.googlesource.com/external/github.com/flutter/flutter/+/c2e85e67c96838449369b1a7177316ae7c574d48
diff --git a/commits.json b/commits.json
index 1a82c2c..e732bda 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "external/github.com/flutter/engine":"e50219fdc5cc7ac2e754052e00226a6436e26b66",
-  "external/github.com/flutter/flutter":"191c7cbe0b01951afc4b6a95d03d8536c04596ee",
+  "external/github.com/flutter/flutter":"c2e85e67c96838449369b1a7177316ae7c574d48",
   "sdk":"0aa5b0f019b9fb3d2894040107062f650ccb2c9e"
 }
\ No newline at end of file