Make the VM's dart:core and dart:async library patches clean.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index d3b62f69fb59dda151d5db756e868abd91a19172..b5d2f7c808d27db7024913526503561a59f0b2e0 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -13015,8 +13015,8 @@ AstNode* Parser::ParseMapLiteral(TokenPosition type_pos,
     ArgumentListNode* constr_args = new (Z) ArgumentListNode(TokenPos());
     constr_args->Add(new (Z) LiteralNode(literal_pos, key_value_array));
     const Function& map_constr = Function::ZoneHandle(
-        Z, immutable_map_class.LookupConstructor(Library::PrivateCoreLibName(
-               Symbols::ImmutableMapConstructor())));
+        Z, immutable_map_class.LookupConstructorAllowPrivate(
+               Symbols::ImmutableMapConstructor()));
     ASSERT(!map_constr.IsNull());
     const Object& constructor_result = Object::Handle(
         Z, EvaluateConstConstructorCall(immutable_map_class, map_type_arguments,