Support multiple categories per message.

pkg/compiler/lib/src/diagnostics/generated/shared_messages.dart

 // Copyright (c) 2015, 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.
 /*
 DON'T EDIT. GENERATED. DON'T EDIT.
 This file has been generated by 'publish.dart' in the dart_messages package.
 
 Messages are maintained in `lib/shared_messages.dart` of that same package.
 After any change to that file, run `bin/publish.dart` to generate a new version
 of the json, dart2js and analyzer representations.
@@ skipping 102 matching lines @@
       r"""
         foo() async* { return 0; }
         main() => foo();
         """,
       r"""
         foo() sync* { return 0; }
         main() => foo();
         """,
     ]
   ),  // Generated. Don't edit.
+  MessageKind.NOT_ASSIGNABLE: const MessageTemplate(
+    MessageKind.NOT_ASSIGNABLE,
+    "'#{fromType}' is not assignable to '#{toType}'."  ),  // Generated. Don't edit.
+  MessageKind.FORIN_NOT_ASSIGNABLE: const MessageTemplate(
+    MessageKind.FORIN_NOT_ASSIGNABLE,
+    "The element type '#{currentType}' of '#{expressionType}' is not assignable to '#{elementType}'.",
+    examples: const [
+      r"""
+        main() {
+          List<int> list = <int>[1, 2];
+          for (String x in list) x;
+        }
+        """,
+    ]
+  ),  // Generated. Don't edit.
 };