Add assert-in-initializer-list to formal specification.

tests/language/assertion_initializer_const_function_test.dart

+// Copyright (c) 201, the Dart project authors.  Please see the AUTHORS file

[eernst, 2017/07/03 16:36:37]

Typo: `2017`.

[Lasse Reichstein Nielsen, 2017/07/04 09:42:18]

good catch

+// 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.
+// VMOptions=--assert_initializer
+//
+// Dart test program testing assert statements.
+
+import "package:expect/expect.dart";
+
+class C {
+  static bool staticTrue() => true;
+  final int x;
+  const C(this.x);
+  // The expression *is* compile-time constant, but not a bool value.
+  // Static warning, runtime always fails assertion.
+  const C.bc01(this.x, y) : assert(staticTrue);  //# 01: static type warning
+}
+
+main() {
+  bool checkedMode = false;
+  assert(checkedMode = true);
+  if (checkedMode) {
+    Expect.throws(() => new C.bc01(1, 2), (e) => e is AssertionError);  //# 01: continued

[eernst, 2017/07/03 16:36:37]

This test file as a whole would go away if we change the treatment of
`assert(staticTrue)` to make it a compile-time error for the declaration of
C.bc01.

[eernst, 2017/07/04 09:09:20]

Next iteration: We keep `assert(staticTrue)` as a static warning and not an
error. When reaching this point, however, the failure might not be an
`AssertionError` (it's misleading, so I'm proposing to make it some other
error).

[Lasse Reichstein Nielsen, 2017/07/04 09:42:17]

I was actually expecting this to be a type error. I can see that I failed to
make it one.

Asserts are only enabled in checked mode, and the problem is that the value is
not a bool.
If I fix the spec, then this will properly throw in checked mode. 

I don't know if that's exactly what the VM does, but it should be possible to
fix.

+  } else {
+    Expect.equals(1, new C.bc01(1, 2).x);  //# 01: continued
+  }
+}