Remove unnecessary imports from front_end

Bug: https://github.com/dart-lang/sdk/issues/44569
Change-Id: I646f5994b40f2007f8d8d4b5ef35e2c9ffbd2376
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/213423
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>
diff --git a/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart b/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
index ad3885a..4fff165 100644
--- a/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/constructor_tearoff_lowering.dart
@@ -6,7 +6,6 @@
 import 'package:kernel/type_algebra.dart';
 import '../builder/member_builder.dart';
 import '../source/source_library_builder.dart';
-import 'kernel_api.dart';
 import 'kernel_helper.dart';
 
 const String _tearOffNamePrefix = '_#';