LibJS: Add "name" property to functions

Author: https://github.com/linusg
Commit: 99be27b4a1
Pull-request: https://github.com/SerenityOS/serenity/pull/2068

Libraries/LibJS/Tests/function-name.js

@@ -0,0 +1,21 @@
+load("test-common.js");
+
+try {
+    var f = function () { }
+    assert(f.name === "");
+    assert((f.name = "f") === "f");
+    assert(f.name === "");
+
+    function foo() { }
+    assert(foo.name === "foo");
+    assert((foo.name = "bar") === "bar");
+    assert(foo.name === "foo");
+
+    assert(console.log.name === "log");
+    assert((console.log.name = "warn") === "warn");
+    assert(console.log.name === "log");
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}