Check that const-map keys don't override equals.

sdk/lib/_internal/compiler/implementation/warnings.dart

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index 8cef76fbfc30e67ba7e4dda467e676eae8bccd91..c71f995cdeb3c0d859f1be8bb30dff5b501693aa 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -556,8 +556,9 @@ main() => new C<String>();
   static const MessageKind CONSTRUCTOR_IS_NOT_CONST = const MessageKind(
       "Constructor is not a 'const' constructor.");
 
-  static const MessageKind KEY_NOT_A_STRING_LITERAL = const MessageKind(
-      "Map-literal key not a string literal.");
+  static const MessageKind CONST_MAP_KEY_OVERRIDES_EQUALS =
+      const MessageKind(
+          "Const-map key '#{type}' overrides 'operator =='.");

[karlklose, 2014/03/03 08:58:45]

I would say 'Const-map key *type* '#type' ...' (see also
SWITCH_CASE_VALUE_OVERRIDES_EQUALS).

[floitsch, 2014/03/03 09:52:32]

Done.

 
   static const MessageKind NO_SUCH_LIBRARY_MEMBER = const MessageKind(
       "'#{libraryName}' has no member named '#{memberName}'.");