Use normal equality for const maps.

tests/language/const_map_test.dart

Index: tests/language/const_map_test.dart
diff --git a/tests/compiler/dart2js_extra/16407_test.dart b/tests/language/const_map_test.dart
similarity index 53%
copy from tests/compiler/dart2js_extra/16407_test.dart
copy to tests/language/const_map_test.dart
index aff1ba337ddab1eb5d219ac635653b48d4f8d1bc..de30f8a1fb9b49c4c6d76e6bc6eacce3a5166d10 100644
--- a/tests/compiler/dart2js_extra/16407_test.dart
+++ b/tests/language/const_map_test.dart
@@ -4,13 +4,13 @@
 
 import "package:expect/expect.dart";
 
-// Regression test for Issue 16407.
-
-void main() {
-  foo(null, true);
-  foo('x', false);
+confuse(x) {

[Lasse Reichstein Nielsen, 2014/03/03 10:31:24]

Document "confuse": Used to prevent static optimizations and inlining by naking
the value too hard to predict at compile time.

[floitsch, 2014/03/03 10:42:38]

Done.

+  if (new DateTime.now() == 42) return confuse(2);
+  return x;
 }
 
-var foo = (x, result) {
-  Expect.equals(result, x is Null, '$x is Null');
-};
+main() {
+  // Make sure that const maps use the == operator and not identical.

[Lasse Reichstein Nielsen, 2014/03/03 10:31:24]

Way that the spec doesn't require this explicitly, but it does so implicitly (by
allowing int and String keys even if they override operator==).

Luckily the VM agrees.

(And, also luckliy, you can't use doubles as keys, or we would have to figure
out what const{1:42,1.0:37} would mean :).

[floitsch, 2014/03/03 10:42:38]

Added string test and added more comment.

+  var m = const { 1: 42 };
+  Expect.equals(42, m[confuse(1.0)]);
+}