Implement fullNameForErrors on all Builders.

pkg/front_end/lib/src/fasta/builder/class_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.class_builder;
 
 import '../errors.dart' show internalError;
 
 import 'builder.dart'
     show
@@ skipping 75 matching lines @@
     if (builder?.next != null) {
       Builder getterBuilder;
       Builder setterBuilder;
       Builder current = builder;
       while (current != null) {
         if (current.isGetter && getterBuilder == null) {
           getterBuilder = current;
         } else if (current.isSetter && setterBuilder == null) {
           setterBuilder = current;
         } else {
-          return new AmbiguousBuilder(builder, charOffset, fileUri);
+          return new AmbiguousBuilder(name, builder, charOffset, fileUri);
         }
         current = current.next;
       }
       builder = isSetter ? setterBuilder : getterBuilder;
     }
     if (builder == null) {
       return null;
     } else if (isSetter && builder.isGetter) {
       return null;
     } else {
@@ skipping 59 matching lines @@
             argument = argument.subst(substitutionMap);
           }
           directSubstitutionMap[variables[i]] = argument;
         }
         substitutionMap = directSubstitutionMap;
       }
     }
     return substitutionMap;
   }
 }