LibJS: Support multiple arguments in Array.prototype.push()

Libraries/LibJS/Tests/Array.prototype.push.js

@@ -0,0 +1,30 @@
+load("test-common.js");
+
+try {
+    assert(Array.prototype.push.length === 1);
+
+    var a = ["hello"];
+    var length = a.push();
+    assert(length === 1);
+    assert(a.length === 1);
+    assert(a[0] === "hello");
+
+    length = a.push("friends");
+    assert(length === 2);
+    assert(a.length === 2);
+    assert(a[0] === "hello");
+    assert(a[1] === "friends");
+
+    length = a.push(1, 2, 3);
+    assert(length === 5);
+    assert(a.length === 5);
+    assert(a[0] === "hello");
+    assert(a[1] === "friends");
+    assert(a[2] === 1);
+    assert(a[3] === 2);
+    assert(a[4] === 3);
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}