JS backend: support secondary constructors in native classes

js/js.translator/testData/native/cases/secondaryConstructor.kt

@@ -0,0 +1,24 @@
+package foo
+
+native
+class A {
+    constructor()
+    constructor(s: String)
+    constructor(i: Int)
+
+    val value: Any?
+}
+
+fun test(a: A, expectedValue: Any?, expectedTypeOfValue: String) {
+    assertTrue(a is A)
+    assertEquals(expectedValue, a.value)
+    assertEquals(expectedTypeOfValue, typeof(a.value))
+}
+
+fun box(): String {
+    test(A(), undefined, "undefined")
+    test(A("foo"), "foo", "string")
+    test(A(124), 124, "number")
+
+    return "OK"
+}

js/js.translator/testData/native/native/secondaryConstructor.js

@@ -0,0 +1,3 @@
+function A(value) {
+    this.value = value
+}