Migrate tests for initializing formals

pkg/dev_compiler/test/codegen/language/initializing_formal_access_test.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+//
+// DartOptions=--initializing-formal-access
+// VMOptions=--initializing-formal-access
+
+import "package:expect/expect.dart";
+
+class C {
+  final int x;
+  final int y;
+
+  const C.constant(this.x) : y = x + 1;
+
+  C(this.x) : y = x + 1 {
+    int z = x + 2;
+    assert(z == y + 1);
+  }
+}
+
+main() {
+  C c = new C(2);
+  Expect.equals(c.x, 2);
+  Expect.equals(c.y, 3);
+  const C cc = const C.constant(4);
+  Expect.equals(cc.x, 4);
+  Expect.equals(cc.y, 5);
+}