Remove some additional code that depended on the old type propagation.

pkg/kernel/testcases/type-propagation/argument.baseline.txt

-library;
-import self as self;
-import "dart:core" as core;
-
-abstract class Base extends core::Object {
-  constructor •() → void
-    : super core::Object::•()
-    ;
-}
-class Foo extends self::Base {
-  constructor •() → void
-    : super self::Base::•()
-    ;
-}
-class Bar extends self::Base {
-  constructor •() → void
-    : super self::Base::•()
-    ;
-}
-class Baz extends self::Base {
-  constructor •() → void
-    : super self::Base::•()
-    ;
-}
-static method foo(dynamic/self::Foo! {other} x) → void/Null {}
-static method bar(dynamic/self::Bar! {other} x) → void/Null {}
-static method foo_escaped(dynamic/core::Object+ {*} x) → void/Null {}
-static method bar_escaped(dynamic/core::Object+ {*} x) → void/Null {}
-static method escape(dynamic/core::Function* {other} fn) → void/Null {
-  fn.call(new self::Baz::•());
-}
-static method main() → dynamic/Null {
-  self::foo(new self::Foo::•());
-  self::bar(new self::Bar::•());
-  self::escape(self::foo_escaped);
-  self::escape(self::bar_escaped);
-}