Roll Flutter from f146e90fbb19 to 99475b1b0bee (11 revisions) (#2619)

diff --git a/.ci/flutter_master.version b/.ci/flutter_master.version
index f7a3ea9..a9baeda 100644
--- a/.ci/flutter_master.version
+++ b/.ci/flutter_master.version
@@ -1 +1 @@
-f146e90fbb199d49a264755465847a74faf8980f
+99475b1b0bee6ab09d0282b255c6b8c7e01ca4fe