Skip language/large_class_declaration_test in debug mode on the vm

tests/language/language.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.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 [ $compiler == none ]
 mixin_super_constructor_named_test: Fail # Issue 12631
 mixin_super_constructor_positionals_test: Fail # Issue 12631
@@ skipping 45 matching lines @@
 
 [ $compiler == none || $compiler == dart2dart]
 # Non-contractive types are not supported in the vm.
 cyclic_type_test/02: Fail, OK
 cyclic_type_test/04: Fail, OK
 cyclic_type2_test: Fail, OK
 least_upper_bound_expansive_test/*: Fail, OK
 
 [ $compiler == none && $runtime == vm ]
 class_keyword_test/02: MissingCompileTimeError # Issue 13627
-
+large_class_declaration_test: Skip # Issue 21343
 unicode_bom_test: Fail # Issue 16067
 
 [ $compiler == none && $checked ]
 type_variable_bounds4_test/01: Fail # Issue 14006
 
 [ $compiler == none ]
 dynamic_prefix_core_test/01: RuntimeError # Issue 12478
 
 [ $compiler == none && ($runtime == vm || $runtime == drt || $runtime == dartium|| $runtime == ContentShellOnAndroid) ]
 dynamic_prefix_core_test/none: Fail # Issue 12478
@@ skipping 37 matching lines @@
 stack_overflow_test: Skip # Crashes. Issue 17440.
 stack_overflow_stacktrace_test: Skip # Crashes. Issue 17440.
 large_class_declaration_test: Skip # Times out. Issue 20352
 
 [ $compiler == none && ($runtime == dartium || $runtime == drt || $runtime == ContentShellOnAndroid) && $mode == debug ]
 large_class_declaration_test: Skip # Times out. Issue 20352
 
 [ $compiler == none && $runtime == ContentShellOnAndroid ]
 gc_test: Skip # Times out flakily. Issue 20956