Revert various changes to Link factories.

dart/frog/type.dart

Index: dart/frog/type.dart
diff --git a/dart/frog/type.dart b/dart/frog/type.dart
index 0b2ca65a71b0b988fbd5aeb874ab7221acaff877..02393f540f96b48d9d92b3093172814f26906dbf 100644
--- a/dart/frog/type.dart
+++ b/dart/frog/type.dart
@@ -527,6 +527,8 @@ class ConcreteType extends Type {
       if (!genericMember.declaringType.isGeneric) return genericMember;
       var newDeclaringType =
         genericMember.declaringType.getOrMakeConcreteType(typeArgsInOrder);
+      var factory = newDeclaringType.getFactory(genericType, constructorName);
+      if (factory !== null) return factory;
       return newDeclaringType.getConstructor(constructorName);
     }