Update dart2js diagnostics to prepare for filtering.

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

Index: sdk/lib/_internal/compiler/implementation/tree_validator.dart
diff --git a/sdk/lib/_internal/compiler/implementation/tree_validator.dart b/sdk/lib/_internal/compiler/implementation/tree_validator.dart
index 5204ed63b393437ce366c4d15f6cdec4d4dab7f5..399ad60ed6ea70ac4bca52bdfcc74b36ce7b46aa 100644
--- a/sdk/lib/_internal/compiler/implementation/tree_validator.dart
+++ b/sdk/lib/_internal/compiler/implementation/tree_validator.dart
@@ -16,7 +16,7 @@ class TreeValidatorTask extends CompilerTask {
     void report(node, message) {
       final error = new InvalidNodeError(node, message);
       errors.add(error);
-      compiler.reportWarning(node, message);
+      compiler.reportWarning(node, MessageKind.GENERIC, {'text': message});
     };
     final validator = new ValidatorVisitor(report);
     tree.accept(new TraversingVisitor(validator));