[JS BE] add tests for es6-classes

js/js.translator/testData/box/es6classes/defaultPrimaryExtendsExternal.kt

@@ -0,0 +1,39 @@
+//IGNORE_BACKEND: JS, JS_IR
+
+var sideEffect = ""
+
+open external class E()
+abstract class A : E {
+    fun print(a: Any) { sideEffect += "#$a" }
+
+    constructor(x: Int, y: Int) : super() {
+        print(x + y)
+        print(foo())
+    }
+
+    constructor(x: Int) : super() {
+        print(x)
+        print(foo())
+    }
+
+    abstract fun foo(): String
+
+    init {
+        print("init: " + foo())
+    }
+}
+
+class O(val x: String) {
+    inner class I() : A(1337) {
+        override fun foo() = x
+    }
+}
+
+fun box(): String {
+    val o = O("OK")
+    val i = o.I()
+
+    assertEquals("#init: OK#1337#OK", sideEffect)
+
+    return i.foo()
+}