Use printUnexpected and add location information.

pkg/front_end/lib/src/fasta/builder/library_builder.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.library_builder;
 
 import '../combinator.dart' show
     Combinator;
 
 import '../errors.dart' show
     InputError,
-    internalError;
+    internalError,
+    printUnexpected;
 
 import '../export.dart' show
     Export;
 
 import '../loader.dart' show
     Loader;
 
 import '../util/relativize.dart' show
     relativizeUri;
 
@@ skipping 33 matching lines @@
 
   Builder addBuilder(String name, Builder builder, int charOffset);
 
   void addExporter(LibraryBuilder exporter, List<Combinator> combinators,
       int charOffset) {
     exporters.add(new Export(exporter, this, combinators, charOffset));
   }
 
   void addCompileTimeError(int charOffset, Object message, [Uri fileUri]) {
     fileUri ??= this.fileUri;
-    InputError error = new InputError(fileUri, charOffset, message);
-    compileTimeErrors.add(error);
-    print(error.format());
+    printUnexpected(fileUri, charOffset, message);
+    compileTimeErrors.add(new InputError(fileUri, charOffset, message));
   }
 
   bool addToExportScope(String name, Builder member);
 
   void addToScope(String name, Builder member);
 
   Builder buildAmbiguousBuilder(
       String name, Builder builder, Builder other, int charOffset);
 
   int finishStaticInvocations() => 0;
@@ skipping 23 matching lines @@
       } else if (constructor.isFactory) {
         return constructor;
       }
     }
     throw internalError("Internal error: No constructor named"
         " '$className::$constructorName' in '$uri'.");
   }
 
   int finishTypeVariables(ClassBuilder object) => 0;
 }