Improve error-recovery from unmatched braces.

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

Index: dart/sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/warnings.dart b/dart/sdk/lib/_internal/compiler/implementation/warnings.dart
index 2c361748cc64d9d3d7006f2c7b90fbe074186ad4..212df609b1b0cddff3f752b0fc0bf8c8cf17b179 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -1766,6 +1766,15 @@ main() => r'''
 main() => r\"\"\"
 """]);
 
+  static const MessageKind UNMATCHED_TOKEN = const MessageKind(
+      "Can't find '#{end}' to match '#{begin}'.",
+      howToFix: DONT_KNOW_HOW_TO_FIX,
+      examples: const[
+          "main(",
+          "main(){",
+          "main(){]}",

[ahe, 2014/04/24 13:08:33]

These three examples are tests. They are exercised by
dart/tests/compiler/dart2js/message_kind_test.dart which uses reflection to run
through all these messages looking for examples and make sure they produce the
expected error messages when analyzed.

Incidentally, message_kind_test reuses the compiler, something I plan to use in
Try Dart. Most of the examples in this file are analyzed in a few milliseconds
(and this is when the compiler is running in checked mode which is a bit slow).

+        ]);
+
   static const MessageKind UNTERMINATED_TOKEN = const MessageKind(
       // This is a fall-back message that shouldn't happen.
       "Incomplete token.");