Update the tests testing the use of built in identifiers

tests/language/built_in_identifier_illegal_test.dart

Index: tests/language/built_in_identifier_illegal_test.dart
diff --git a/tests/language/pseudo_kw_illegal_test.dart b/tests/language/built_in_identifier_illegal_test.dart
similarity index 90%
rename from tests/language/pseudo_kw_illegal_test.dart
rename to tests/language/built_in_identifier_illegal_test.dart
index 32d80413563ad8647a525393cd55ea6b4a40a72a..f78b421297c1ef708699e2cee50e0620a16ac471 100644
--- a/tests/language/pseudo_kw_illegal_test.dart
+++ b/tests/language/built_in_identifier_illegal_test.dart
@@ -5,9 +5,10 @@
 
 // Pseudo keywords are not allowed to be used as class names.
 class abstract { }    /// 01: compile-time error
-class assert { }      /// 02: compile-time error
+class as { }          /// 18: compile-time error
 class dynamic { }     /// 04: compile-time error
 class export { }      /// 17: compile-time error
+class external { }    /// 19: compile-time error
 class factory { }     /// 05: compile-time error
 class get { }         /// 06: compile-time error
 class implements { }  /// 07: compile-time error
@@ -19,4 +20,5 @@ class set { }         /// 13: compile-time error
 class static { }      /// 15: compile-time error
 class typedef { }     /// 16: compile-time error
 
+
 main() { }