[JS BE] add tests for es6-classes

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

@@ -0,0 +1,30 @@
+// EXPECTED_REACHABLE_NODES: 1344
+open class A(var value: Int) {
+    init {
+        value *= 2
+    }
+}
+
+class B : A {
+    init {
+        value /= 6
+    }
+
+    constructor(x: Int) : super(x) {
+        value *= 18
+    }
+
+    constructor() : this(18) {
+        value *= 12
+    }
+}
+
+fun box(): String {
+    val bs1 = B(15)
+    assertEquals(90, bs1.value)
+
+    val bs2 = B()
+    assertEquals(72 * 18, bs2.value)
+
+    return "OK"
+}