JS: enable test after bootstrap

Check that a custom Promise declaration is supported for the @AfterTest
annotation functionality in the kotlin.test library

This is a part of the fix for KT-63359


Merge-request: KT-MR-14333
Merged-by: Anton Bannykh <Anton.Bannykh@jetbrains.com>

libraries/kotlin.test/js/it/src/test/kotlin/MainTest.kt

@@ -86,9 +86,9 @@ class AsyncTest {
     }
 
     @Test
+    @Suppress("CAST_NEVER_SUCCEEDS")
     fun checkCustomPromise(): CustomPromise {
-//        return promise(10, "afterCustom") as CustomPromise
+        return promise(10, "afterCustom") as CustomPromise
-        return promise(10, "") as CustomPromise
     }
 
     @Test