Update flutter DEPS to dart d684a576a6aa954ae107a03b2b4e1d61c3bebe93

Author: flutteractionsbot

DEPS

@@ -59,7 +59,7 @@ vars = {
   # updated revision list of existing dependencies. You will need to
   # gclient sync before and after update deps to ensure all deps are updated.
   # updated revision list of existing dependencies.
-  'dart_revision': 'fc3da898ea1664b8a8633f6ec03d2c2290bb3d01',
+  'dart_revision': 'd684a576a6aa954ae107a03b2b4e1d61c3bebe93',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -304,7 +304,7 @@ deps = {
    Var('dart_git') + '/core.git' + '@' + Var('dart_core_rev'),
 
   'engine/src/flutter/third_party/dart/third_party/pkg/dart_style':
-   Var('dart_git') + '/dart_style.git@9b302dd20b4b38979352f21cf515b44617d344ce',
+   Var('dart_git') + '/dart_style.git@20ab21773a526f480ca5948f32cf8c77e37d0dc9',
 
   'engine/src/flutter/third_party/dart/third_party/pkg/dartdoc':
    Var('dart_git') + '/dartdoc.git@a57f497ae9df6e6073b5eb7ddf253d0b2eb470c3',