Opt-in to generate code for compile-time error. Only supported for SSA.

tests/compiler/dart2js/mock_compiler.dart

Index: tests/compiler/dart2js/mock_compiler.dart
diff --git a/tests/compiler/dart2js/mock_compiler.dart b/tests/compiler/dart2js/mock_compiler.dart
index f6c9cc87e433443859e1235213ee62db24650663..3d879dfc9cc15a0b6799f869856fbe05d5150784 100644
--- a/tests/compiler/dart2js/mock_compiler.dart
+++ b/tests/compiler/dart2js/mock_compiler.dart
@@ -389,9 +389,9 @@ api.DiagnosticHandler createHandler(MockCompiler compiler, String text,
       sourceFile = compiler.sourceFiles[uri.toString()];
     }
     if (sourceFile != null && begin != null && end != null) {
-      print(sourceFile.getLocationMessage(message, begin, end));
+      print('${kind}: ${sourceFile.getLocationMessage(message, begin, end)}');
     } else {
-      print(message);
+      print('${kind}: $message');
     }
   };
 }