Roll src/third_party/dart 6354b0b97d..d166b0be1c (4 commits)

dart-lang/sdk@d166b0be1c [dartdevc] Reorganize and add some NNBD subtype test cases
dart-lang/sdk@12c5eaae27 Issue 39089. Don't consider postfix bang as setter context.
dart-lang/sdk@1c187adbad Issue 38583. Don't resolve type of this in extension to bounds.
dart-lang/sdk@a3ca5c3c54 [analysis_server] remove session id from connected params

DEPS

@@ -34,7 +34,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': '6354b0b97dced6c0cdee8f22009b4351f0095d75',
+  'dart_revision': 'd166b0be1cde1a82bfb8317693e8477530b37c58',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py