Expect dart2dart to fail on string_split_test.

tests/corelib/corelib.status

 # Copyright (c) 2012, 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.
 
 [ $compiler == dart2dart]
 bool_from_environment2_test: Skip
 bool_from_environment_default_value_test: Skip
 bool_from_environment_test: Skip
 from_environment_const_type_test: Skip
 from_environment_const_type_undefined_test: Skip
@@ skipping 125 matching lines @@
 [ $compiler == dart2js && ($runtime == ff || $runtime == jsshell) ]
 string_case_test/01: Fail, OK  # Bug in Firefox.
 
 [ $compiler == dart2js && $runtime == dartium ]
 string_case_test/02: Fail, OK  # Bug in dartium version of V8.
 string_case_test/03: Fail, OK  # Bug in dartium version of V8.
 
 [ $compiler == dart2dart ]
 compare_to2_test: Fail # inherited from VM
 unicode_test: Fail # inherited from VM
+string_split_test: RuntimeError # Issue 21441.
 
 [ $compiler == dart2dart && $minified ]
 error_stack_trace1_test: Fail # Fails in minified mode, test depends on method names.
 
 [ $compiler == dartanalyzer ]
 int_parse_radix_test: Fail, OK # Test contains errors but doesn’t mark them as expected
 list_insert_test: Fail, OK # Test contains errors but doesn’t mark them as expected
 list_removeat_test: Fail, OK # Test contains errors but doesn’t mark them as expected
 
 # Issue 16391. These tests are supposed to produce a compile time
@@ skipping 55 matching lines @@
 num_clamp_test: StaticWarning, OK # Test generates errors on purpose.
 string_test: StaticWarning, OK # Test generates error on purpose.
 
 [ $runtime == ie10 ]
 num_parse_test: RuntimeError  # Issue 15316
 num_parse_test/01: RuntimeError  # Issue 15316
 
 [ $system == windows && $arch == x64 ]
 stopwatch_test: Skip  # Flaky test due to expected performance behaviour.