JS: when RHS of as cast is non-nullable native interface, check LHS for null

js/js.translator/testData/box/native/castToNativeInterfaceChecked.kt

@@ -0,0 +1,15 @@
+@native interface I {
+    fun foo(): String
+}
+
+fun createObject(): Any? = null
+
+fun box(): String {
+    try {
+        (createObject() as I).foo()
+        return "fail: exception not thrown"
+    }
+    catch (e: ClassCastException) {
+        return "OK"
+    }
+}