remove field override, assign to super field instead (#135165)

Removes an ignore about overriding fields. Instead we just assign the value to the original field in the super class.

Related to https://github.com/dart-lang/language/issues/3332 (discovered during investigations into the violation of that lint).
https://dart.googlesource.com/external/github.com/flutter/flutter/+/daea6e00bfc0452cbd3b1c46f3dd2d41a05da0a7

DEPS

diff --git a/DEPS b/DEPS
index 69c3453..4d41ffc 100644
--- a/DEPS
+++ b/DEPS
@@ -269,7 +269,7 @@
 
   'engine/src/third_party/dart': Var('dart_git') + '/sdk' + '@' + 'd54f0acd02f8c330d1e5ad79e1239a72d6deb20e',
 
-  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '528a281a5c89c9bb91e6c6d1f90ebc1376a3809b',
+  'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + 'daea6e00bfc0452cbd3b1c46f3dd2d41a05da0a7',
 
    # Fuchsia compatibility
    #

commits.json

diff --git a/commits.json b/commits.json
index 28a4e8b..7b9960f 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "engine/src/flutter":"a0261dd7310726d90e9d3bb7cb282b799d7e6cd1",
   "engine/src/third_party/dart":"d54f0acd02f8c330d1e5ad79e1239a72d6deb20e",
-  "flutter":"528a281a5c89c9bb91e6c6d1f90ebc1376a3809b"
+  "flutter":"daea6e00bfc0452cbd3b1c46f3dd2d41a05da0a7"
 }
\ No newline at end of file