fix list_test for strong mode, and fix DDC List constructors

tests/corelib_2/corelib_2.status

Index: tests/corelib_2/corelib_2.status
diff --git a/tests/corelib_2/corelib_2.status b/tests/corelib_2/corelib_2.status
index 70e590256f4d212edcc494c1e69ebf3173da200a..37c187a6f17b7a73074036f429cc12b907872125 100644
--- a/tests/corelib_2/corelib_2.status
+++ b/tests/corelib_2/corelib_2.status
@@ -96,8 +96,7 @@ growable_list_test: RuntimeError # Issue 29921
 hash_set_test/01: RuntimeError # Issue 29921
 iterable_reduce_test/none: RuntimeError
 iterable_to_list_test/*: RuntimeError
-list_test/none: RuntimeError
-list_test/01: RuntimeError
+list_concurrent_modification_test: RuntimeError # DDC uses ES6 array iterators so it does not issue this
 nan_infinity_test/01: RuntimeError # Issue 29921
 null_nosuchmethod_test: RuntimeError # Issue 29921
 main_test: RuntimeError # Issue 29921
@@ -181,6 +180,7 @@ integer_to_string_test/01: RuntimeError
 iterable_to_set_test: RuntimeError # is-checks do not implement strong mode type system
 int_parse_radix_test/01: RuntimeError
 int_parse_radix_test/02: RuntimeError
+list_test/*: RuntimeError # dart2js doesn't implement strong mode covariance checks
 
 [ $compiler == dart2js && $runtime == drt && $csp && $minified ]
 core_runtime_types_test: Pass, Fail # Issue 27913
@@ -326,6 +326,7 @@ big_integer_parsed_mul_div_vm_test: Pass, Timeout # --no_intrinsify
 string_trimlr_test/02: RuntimeError # Issue 29060
 iterable_to_set_test: RuntimeError # is-checks do not implement strong mode type system
 
+
 [ $compiler == precompiler || $compiler == app_jit ]
 string_trimlr_test/02: RuntimeError # Issue 29060
 
@@ -936,6 +937,9 @@ splay_tree_from_iterable_test: RuntimeError
 regexp/pcre_test: Pass, Slow, Timeout
 regexp/global_test: Skip # Issue 21709
 
+[ $runtime == vm || $runtime == dart_precompiled ]
+list_test/*: RuntimeError # VM doesn't implement strong mode covariance checks
+
 [ $mode == debug ]
 regexp/pcre_test: Pass, Slow # Issue 22008