Issue 3531. Don't allow using built-in identifier as import prefix

tests/language/pseudo_kw_illegal_test.dart

Index: tests/language/pseudo_kw_illegal_test.dart
diff --git a/tests/language/pseudo_kw_illegal_test.dart b/tests/language/pseudo_kw_illegal_test.dart
index 60ec6d60616fab4d0e93ce897f8802377f79ce56..4a4b93e6821665605baf21397f703845a09c9458 100644
--- a/tests/language/pseudo_kw_illegal_test.dart
+++ b/tests/language/pseudo_kw_illegal_test.dart
@@ -6,7 +6,6 @@
 // Pseudo keywords are not allowed to be used as class names.
 class abstract { }    /// 01: compile-time error
 class assert { }      /// 02: compile-time error
-class call { }        /// 03: compile-time error
 class Dynamic { }     /// 04: compile-time error
 class factory { }     /// 05: compile-time error
 class get { }         /// 06: compile-time error