Actually update flutter rev (#566)

diff --git a/flutter b/flutter
index f994b76..8fe7655 160000
--- a/flutter
+++ b/flutter
@@ -1 +1 @@
-Subproject commit f994b769743368b36b9c03fb359f62230b60ab92
+Subproject commit 8fe7655ed20ffd1395f68e30539a847a01a30351