Implement line and column numbers.

pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
index 48dcceeec373ea9f2b9ab8647fea0c822b469d21..e5b93586d48b28246cf4ac92cbc1029bf3a2fd3b 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_class_builder.dart
@@ -17,6 +17,9 @@ import 'package:kernel/ast.dart' show
 import '../errors.dart' show
     internalError;
 
+import '../messages.dart' show
+    warning;
+
 import 'kernel_builder.dart' show
     Builder,
     ClassBuilder,
@@ -105,9 +108,9 @@ abstract class KernelClassBuilder
             } else {
               // TODO(ahe): Throw NSM error. This requires access to core
               // types.
-              String message =
-                  "Missing constructor: ${redirectionTarget.fullNameForErrors}";
-              print(message);
+              String message = "Redirection constructor target not found: "
+                  "${redirectionTarget.fullNameForErrors}";
+              warning(library.fileUri, -1, message);
               builder.body = new ExpressionStatement(
                   new Throw(new StringLiteral(message)));
             }