Roll Flutter from c50b02f2c3e6 to c849844feb3d (20 revisions) (#4898)

diff --git a/.ci/flutter_master.version b/.ci/flutter_master.version
index 4d5ae1f..2eebe0e 100644
--- a/.ci/flutter_master.version
+++ b/.ci/flutter_master.version
@@ -1 +1 @@
-c50b02f2c3e69e23b9c044c571d1a34f816d7ab4
+c849844feb3de477b27dfcb3bd6879ca621bccc7