Get non-nullable DartType in _typeStr().

Change-Id: I40a5ed56079a6c3908c1a7cdf7cd796015660eef
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/236303
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analyzer/test/src/summary/resolved_ast_printer.dart b/pkg/analyzer/test/src/summary/resolved_ast_printer.dart
index 317d7c5..18026d6 100644
--- a/pkg/analyzer/test/src/summary/resolved_ast_printer.dart
+++ b/pkg/analyzer/test/src/summary/resolved_ast_printer.dart
@@ -1333,9 +1333,8 @@
     return '{$entriesStr}';
   }
 
-  /// TODO(scheglov) Make [type] non-nullable?
-  String? _typeStr(DartType? type) {
-    return type?.getDisplayString(withNullability: true);
+  String? _typeStr(DartType type) {
+    return type.getDisplayString(withNullability: true);
   }
 
   void _withIndent(void Function() f) {
@@ -1535,8 +1534,12 @@
 
   void _writeType(String name, DartType? type) {
     if (_withResolution) {
-      var typeStr = _typeStr(type);
-      _writelnWithIndent('$name: $typeStr');
+      if (type != null) {
+        var typeStr = _typeStr(type);
+        _writelnWithIndent('$name: $typeStr');
+      } else {
+        _writelnWithIndent('$name: null');
+      }
     }
   }