Fix handling of inline JS types in DDC.

pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart

Index: pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart b/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
index dbba17103ecbab2aa55ccc7736710580ac6de378..45330349f4329dbccb85904126868b4a34b9a5fd 100644
--- a/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
+++ b/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
@@ -184,7 +184,9 @@ abstract class NullableTypeInference {
         var first = args.isNotEmpty ? args.first : null;
         if (first is SimpleStringLiteral) {
           var types = first.stringValue;
-          if (!types.split('|').contains('Null')) {
+          if (types != '' &&
+              types != 'var' &&
+              !types.split('|').contains('Null')) {
             return false;
           }
         }