Remove dart backend

test/dart_codegen/expect/d/d.dart

Index: test/dart_codegen/expect/d/d.dart
diff --git a/test/dart_codegen/expect/d/d.dart b/test/dart_codegen/expect/d/d.dart
deleted file mode 100644
index fd140b274fb29fc0891cccd1bbfbf67617f5d036..0000000000000000000000000000000000000000
--- a/test/dart_codegen/expect/d/d.dart
+++ /dev/null
@@ -1,10 +0,0 @@
-library d;
-import 'a/a.dart' as DDC$a$;
-import 'package:dev_compiler/runtime/dart_logging_runtime.dart' as DEVC$RT;
-import 'b.dart';
- void foo() {
-  var x = f3(((__x0) => DEVC$RT.cast(__x0, dynamic, DDC$a$.A, "DynamicCast", """line 10, column 14 of test/dart_codegen/types/d.dart: """, __x0 is DDC$a$.A, true))(f4("""hello""")));
-   var y = f1(DEVC$RT.cast(f4, __CastType1, DDC$a$.A2A, "CompositeCast", """line 11, column 14 of test/dart_codegen/types/d.dart: """, f4 is DDC$a$.A2A, false));
-   var z = f2(f3);
-  }
- typedef dynamic __CastType1(dynamic __u2);