Move kernel baseline tests to front_end.

pkg/front_end/test/fasta/classes.dart.direct.expect

-library;
-import self as self;
-import "dart:core" as core;
-
-class A extends core::Object {
-  final field core::int x;
-  final field core::int y;
-  constructor •(dynamic y) → void
-    : self::A::y = y, self::A::x = 42, super core::Object::•()
-    ;
-  method method() → dynamic {
-    core::print("A.method x: ${this.x} y: ${this.y}");
-    core::print(this);
-    core::print(this.runtimeType);
-  }
-}
-class B extends self::A {
-  constructor •(dynamic x) → void
-    : super self::A::•(x)
-    ;
-  method method() → dynamic {
-    core::print("B.method x: ${this.x} y: ${this.y}");
-    this.{=self::A::method}();
-  }
-}
-static method main() → dynamic {
-  self::A a = new self::A::•(87);
-  self::B b = new self::B::•(117);
-  a.method();
-  b.method();
-}