Dart2JS dump info duplicates code related to method alias installation

[Markzipan]

Snippet:

//@dart = 2.9

import 'package:expect/expect.dart';

class Super<T> {
  void method(T t) {}
}

class Mixin {
  void method(int t) {}
}

class Clazz = Super<int> with Mixin;

class Subclass extends Clazz {
  void test() {
	super.method(0);
  }
}

main() {
  Super<Object> s = new Subclass()..test();
  Expect.throws(() => s.method(''));
}

Generates function/mix.dart::Mixin.method and function/mix.dart::Clazz.method, both of which have an 81-byte code size overhead:
"code": "method$1(t) {\n }\nvar _ = A.Mixin.prototype;\n\n_.super$Mixin$method = _.method$1;\n",

However, that code snippet only occurs once. I suspect we're overcounting these cases.