[Wasm] Support external vararg

Initial implementation copies Wasm array to JS array and spreads it

compiler/testData/codegen/boxWasmJsInterop/vararg.js

@@ -0,0 +1,77 @@
+function paramCount() {
+    return arguments.length
+}
+
+function Bar(size, order) {
+    this.size = size;
+    Bar.checkOrder(order);
+}
+
+Bar.order = 0;
+Bar.hasOrderProblem = false;
+Bar.checkOrder = function (expectedOrder) {
+    var curOrder = Bar.order++;
+    Bar.hasOrderProblem = Bar.hasOrderProblem || curOrder !== expectedOrder;
+};
+
+Bar.startNewTest = function () {
+    Bar.hasOrderProblem = false;
+    Bar.order = 0;
+    return true;
+};
+
+
+Bar.prototype.test = function (order, dummy /*, args */) {
+    Bar.checkOrder(order);
+    return dummy === 1 && (arguments.length - 2) === this.size;
+};
+Bar.prototype.test2 = Bar.prototype.test;
+
+function test3(bar, dummy  /*, args */) {
+    return dummy === 1 && (arguments.length - 2) === bar.size;
+}
+
+var obj = {
+    test: function (size /*, args */) {
+        return (arguments.length - 1) === size;
+    }
+};
+
+function testNativeVarargWithFunLit(/* args, f */) {
+    var args = Array.prototype.slice.call(arguments, 0, arguments.length - 1);
+    var f = arguments[arguments.length - 1];
+    return typeof f === "function" && f(args);
+}
+
+function sumOfParameters() {
+    var size = arguments.length;
+    var result = 0;
+    for (var i = 0; i < size; i++) {
+        result += arguments[i];
+    }
+    return result;
+}
+
+function sumFunValuesOnParameters() {
+    var size = arguments.length - 1;
+    var f = arguments[arguments.length - 1];
+    var result = 0;
+    for (var i = 0; i < size; i++) {
+        var u = arguments[i];
+        result += f(u);
+    }
+    return result;
+}
+
+function idArrayVarArg() {
+    var args = Array.prototype.slice.call(arguments, 0, arguments.length);
+    return args;
+}
+
+function join(...args) {
+    return args.join("-");
+}
+
+function mapJoin(f, ...args) {
+    return args.map(x => f(x)).join("-")
+}