Make data types null safe (#1615)

* Make data types null safe

* Updated changelog, versions, and built

* Pull null safe dependencies, disable analyzer warning on generated files

* Remove unnecessary build options

* Format

* Update comment in analysis_options.yaml

* Added comments on nullable data fields

* Rephrased comments

* Allow more time for timing out tests

Author: Anna Gringauze

dwds/CHANGELOG.md

@@ -1,4 +1,5 @@
 ## 14.0.3-dev
+- Make data types null safe
 - Update `package:vm_service` to 8.3.0.
 
 ## 14.0.2

dwds/analysis_options.yaml

@@ -0,0 +1,8 @@
+# This file contains the analysis options used for code in the webdev
+# repository.
+
+analyzer:
+  exclude:
+      # Ignore generated files
+    - "lib/data/*"
+

dwds/lib/data/build_result.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:built_collection/built_collection.dart';
 import 'package:built_value/built_value.dart';
 import 'package:built_value/serializer.dart';

dwds/lib/data/build_result.g.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:built_value/built_value.dart';
 import 'package:built_value/serializer.dart';
 

dwds/lib/data/connect_request.dart

@@ -2,8 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// @dart = 2.9
-
 import 'package:built_collection/built_collection.dart';
 import 'package:built_value/built_value.dart';
 import 'package:built_value/serializer.dart';