[JS BE] add tests for es6-classes

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

@@ -0,0 +1,24 @@
+// EXPECTED_REACHABLE_NODES: 1371
+inline class I1(val a: Int)
+inline class I2(val i: I1)
+inline class I3(val i: I2)
+inline class I4(val i: I3)
+inline class I5(val i: I4)
+
+class TestDefault(val def: I5 = I5(I4(I3(I2(I1(999))))))
+
+class TestGen<T>(val gen: T)
+
+fun box(): String {
+    val x = I5(I4(I3(I2(I1(1337)))))
+    assertEquals(1337, x.i.i.i.i.a)
+
+    val testDefault = TestDefault()
+    assertEquals(999, testDefault.def.i.i.i.i.a)
+
+    val testDefaultGen = TestGen(I5(I4(I3(I2(I1(1953))))))
+    assertTrue(testDefault.def.i.i.i.i.a is Int)
+    assertEquals(1953, testDefaultGen.gen.i.i.i.i.a)
+
+    return "OK"
+}