Roll Flutter from 201a64c98f35 to 2f73173c36f8 (3 revisions) (#5047)

diff --git a/.ci/flutter_master.version b/.ci/flutter_master.version
index d17adfe..46c8083 100644
--- a/.ci/flutter_master.version
+++ b/.ci/flutter_master.version
@@ -1 +1 @@
-201a64c98f350dbc88c6fd3f8a6050864f2259cf
+2f73173c36f806c7f30e705a90722082f85a2c8b