JS IR: fix throwable descendants

^ KT-43490 fixed

js/js.translator/testData/box/expression/try/overrideThrowableProperties.kt

@@ -2,20 +2,57 @@
 
 open class Ex0(msg: String, cs: Throwable): Throwable(msg, cs)
 
-class Ex1: Ex0("A", Error("fail2")) {
+open class Ex1: Ex0("A", Error("fail2")) {
     override val cause = Error("B")
 }
 
-class Ex2: Ex0("fail3", Error("C")) {
+open class Ex2: Ex0("fail3", Error("C")) {
     override val message = "D"
 }
 
-fun box(): String {
-    val ex1: Throwable = Ex1()
-    val ex2: Throwable = Ex2()
+open class Ex3: Ex0("fail", Error("fail")) {
+    override val message get() = "O"
 
-    val r = ex1.message + ex1.cause?.message + ex2.cause?.message + ex2.message
-    if (r != "ABCD") return "Fail: $r"
+    override val cause get() = Error("K")
+}
+
+open class Ex4: Ex3()
+
+class Ex5: Ex4() {
+    override val message: String
+        get() = "!"
+}
+
+@JsExport
+open class A : Throwable("AM", Error("AC"))
+
+@JsExport
+open class B : A() {
+    override val message = "BM"
+
+    override val cause = Error("BC")
+}
+
+@JsExport
+class C : B()
+
+fun Throwable.check(expectedMessage: String, expectedCauseMessage: String?) {
+    assertEquals(expectedMessage, message)
+    assertEquals(expectedCauseMessage, cause?.message)
+}
+
+fun box(): String {
+
+    Ex1().check("A", "B")
+    Ex2().check("D", "C")
+
+    Ex3().check("O", "K")
+    Ex4().check("O", "K")
+    Ex5().check("!", "K")
+
+    A().check("AM", "AC")
+    B().check("BM", "BC")
+    C().check("BM", "BC")
 
     return "OK"
 }