Remove corelib/corelib_strong and migrate last two remaining tests.

tests/corelib_strong/corelib_strong.status

Index: tests/corelib_strong/corelib_strong.status
diff --git a/tests/corelib_strong/corelib_strong.status b/tests/corelib_strong/corelib_strong.status
deleted file mode 100644
index 01741b57cb1d2f8fe14fa9425b71efecec456ddf..0000000000000000000000000000000000000000
--- a/tests/corelib_strong/corelib_strong.status
+++ /dev/null
@@ -1,30 +0,0 @@
-# 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.
-
-# Skip entire suite if not running in strong mode.
-[ ! $strong ]
-*: SkipByDesign
-
-# Skip tests that are not yet strong-mode clean.
-[ $strong ]
-duration2_test: Skip
-error_stack_trace_test: Skip
-http_resource_test: Skip
-linked_hash_map_from_iterable_test: Skip
-regexp/regress-regexp-codeflush_test: Skip
-regexp/standalones_test: Skip
-string_replace_test: Skip
-
-[ $compiler == dartdevc && $runtime != none ]
-hash_set_test/01: RuntimeError # Issue 29921
-regress_r21715_test: RuntimeError # Issue 29921
-string_operations_with_null_test: RuntimeError # Issue 29921
-from_environment_const_type_test/01: RuntimeError # Issue 29921
-from_environment_const_type_test/05: RuntimeError # Issue 29921
-from_environment_const_type_test/10: RuntimeError # Issue 29921
-from_environment_const_type_test/15: RuntimeError # Issue 29921
-from_environment_const_type_test/none: RuntimeError # Issue 29921
-growable_list_test: RuntimeError # Issue 29921
-list_test/01: RuntimeError # Issue 29921
-list_test/none: RuntimeError # Issue 29921