Change signature of resolveConstructors.

pkg/front_end/lib/src/fasta/builder/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.builder;
 
 import '../errors.dart' show internalError;
 
 export 'class_builder.dart' show ClassBuilder;
 
@@ skipping 70 matching lines @@
     throw "The relativeFileUri method should be only called on subclasses "
         "which have an efficient implementation of `relativeFileUri`!";
   }
 
   /// Resolve types (lookup names in scope) recorded in this builder and return
   /// the number of types resolved.
   int resolveTypes(covariant Builder parent) => 0;
 
   /// Resolve constructors (lookup names in scope) recorded in this builder and
   /// return the number of constructors resolved.
-  int resolveConstructors(covariant Builder parent) => 0;
+  int resolveConstructors(LibraryBuilder parent) => 0;
 
   Builder get parent => null;
 
   bool get isFinal => false;
 
   bool get isField => false;
 
   bool get isRegularMethod => false;
 
   bool get isGetter => false;
@@ skipping 26 matching lines @@
 
   Uri computeLibraryUri() {
     Builder builder = this;
     do {
       if (builder is LibraryBuilder) return builder.uri;
       builder = builder.parent;
     } while (builder != null);
     return internalError("No library parent.");
   }
 }