JS backend: add support multi declaration

js/js.translator/testFiles/multideclaration/cases/multiValForArray.kt

@@ -0,0 +1,21 @@
+package foo
+class A {
+    fun component1() : Int = 1
+}
+fun A.component2() : String = "n"
+
+fun box(): String {
+    val list = Array<A>(1, {A()})
+
+    var i = 0;
+    var s = ""
+    for ((a,b) in list) {
+        i = a;
+        s = b;
+    }
+
+    if (i != 1) return "i != 1, it: " + i
+    if (s != "n") return "s != 'n', it: " + s
+
+    return "OK"
+}