Implement override checks.

dart/lib/compiler/implementation/warnings.dart

Index: dart/lib/compiler/implementation/warnings.dart
diff --git a/dart/lib/compiler/implementation/warnings.dart b/dart/lib/compiler/implementation/warnings.dart
index 54addb2ae01b40bb02918bbf8f128a59b01b3542..b4b1cec2097d16b15eb58ec458e817ffe7976c54 100644
--- a/dart/lib/compiler/implementation/warnings.dart
+++ b/dart/lib/compiler/implementation/warnings.dart
@@ -179,6 +179,38 @@ class MessageKind {
   static final MISSING_ARGUMENTS_TO_ASSERT = const MessageKind(
       "missing arguments to assert");
 
+  static final GETTER_MISMATCH = const MessageKind(
+      "Error: setter disagrees on: #{1}.");
+
+  static final SETTER_MISMATCH = const MessageKind(
+      "Error: getter disagrees on: #{1}.");
+
+  static final NO_STATIC_OVERRIDE = const MessageKind(
+      "Error: static member cannot override instance member '#{1}' of '#{2}'.");
+
+  static final NO_STATIC_OVERRIDE_CONT = const MessageKind(
+      "Info: this is the instance member that cannot be overridden "
+      "by a static member.");
+
+  static final CANNOT_OVERRIDE_FIELD_WITH_METHOD = const MessageKind(
+      "Error: method cannot override field '#{1}' of '#{2}'.");
+
+  static final CANNOT_OVERRIDE_FIELD_WITH_METHOD_CONT = const MessageKind(
+      "Info: this is the field that cannot be overridden by a method.");
+
+  static final CANNOT_OVERRIDE_METHOD_WITH_FIELD = const MessageKind(
+      "Error: field cannot override method '#{1}' of '#{2}'.");
+
+  static final CANNOT_OVERRIDE_METHOD_WITH_FIELD_CONT = const MessageKind(
+      "Info: this is the method that cannot be overridden by a field.");
+
+  static final BAD_ARITY_OVERRIDE = const MessageKind(
+      "Error: cannot override method '#{1}' in '#{2}'; "
+      "the parameters do not match.");
+
+  static final BAD_ARITY_OVERRIDE_CONT = const MessageKind(
+      "Info: this is the method whose parameters do not match.");
+
   static final COMPILER_CRASHED = const MessageKind(
       "Error: The compiler crashed when compiling this element.");