Patch refactoring.

lib/compiler/implementation/warnings.dart

Index: lib/compiler/implementation/warnings.dart
diff --git a/lib/compiler/implementation/warnings.dart b/lib/compiler/implementation/warnings.dart
index 6c17cf7ffdde4dd857a6748661e9161fe1235ef9..26a236e5c9de0d800ca36b88caea10f960b959a2 100644
--- a/lib/compiler/implementation/warnings.dart
+++ b/lib/compiler/implementation/warnings.dart
@@ -256,6 +256,19 @@ class MessageKind {
   static const VOID_NOT_ALLOWED = const MessageKind(
       'type void is only allowed in a return type.');
 
+  static const PATCH_RETURN_TYPE_MISMATCH = const MessageKind(
+      "Patch return type #{3} doesn't match #{2} on origin method #{1}.");
+
+  static const PATCH_REQUIRED_PARAMETER_COUNT_MISMATCH = const MessageKind(
+      "Required parameter count of patch method (#{3}) on origin method #{1}.");
+
+  static const PATCH_OPTIONAL_PARAMETER_COUNT_MISMATCH = const MessageKind(
+      "Optional parameter count of patch method (#{3}) on origin method #{1}.");
+
+  static const PATCH_PARAMETER_MISMATCH = const MessageKind(
+      "Patch parameter '#{3}' doesn't match '#{2}' on origin method #{1}.");
+
+
   static const COMPILER_CRASHED = const MessageKind(
       "Error: The compiler crashed when compiling this element.");