[JS IR BE] hashCode, toString, number conversion support

compiler/testData/codegen/box/reified/reifiedChain.kt

@@ -1,5 +1,4 @@
 // IGNORE_BACKEND: JVM_IR
-// IGNORE_BACKEND: JS_IR
 inline fun <reified T> Any?.check(): Boolean {
     return this is T
 }
@@ -35,4 +34,4 @@ fun box(): String {
     }
 
     return "OK"
-}
+}