Report messages instead of just printing.

pkg/front_end/lib/src/fasta/loader.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.loader;
 
 import 'dart:async' show Future;
 
 import 'dart:collection' show Queue;
 
 import 'builder/builder.dart' show Builder, LibraryBuilder;
 
-import 'deprecated_problems.dart'
-    show firstSourceUri, deprecated_printUnexpected;
+import 'deprecated_problems.dart' show firstSourceUri;
 
 import 'messages.dart'
     show LocatedMessage, Message, messagePlatformPrivateLibraryAccess;
 
+import 'severity.dart' show Severity;
+
 import 'target_implementation.dart' show TargetImplementation;
 
 import 'ticker.dart' show Ticker;
 
 abstract class Loader<L> {
   final Map<Uri, LibraryBuilder> builders = <Uri, LibraryBuilder>{};
 
   final Queue<LibraryBuilder> unparsedLibraries = new Queue<LibraryBuilder>();
 
   final List<L> libraries = <L>[];
@@ skipping 138 matching lines @@
   /// Register [message] as a compile-time error.
   ///
   /// If [silent] is true, no error is printed as it is assumed the error has
   /// been previously reported.
   ///
   /// If [wasHandled] is true, this error is added to [handledErrors],
   /// otherwise it is added to [unhandledErrors].
   void addCompileTimeError(Message message, int charOffset, Uri fileUri,
       {bool silent: false, bool wasHandled: false}) {
     if (!silent) {
-      deprecated_printUnexpected(fileUri, charOffset, message.message);
+      target.context
+          .report(message.withLocation(fileUri, charOffset), Severity.error);
     }
     (wasHandled ? handledErrors : unhandledErrors)
         .add(message.withLocation(fileUri, charOffset));
   }
 
   Builder getAbstractClassInstantiationError() {
     return target.getAbstractClassInstantiationError(this);
   }
 
   Builder getCompileTimeError() => target.getCompileTimeError(this);
 
   Builder getDuplicatedFieldInitializerError() {
     return target.getDuplicatedFieldInitializerError(this);
   }
 
   Builder getNativeAnnotation() => target.getNativeAnnotation(this);
 }
 
 String format(double d, int fractionDigits, int width) {
   return d.toStringAsFixed(fractionDigits).padLeft(width);
 }