LibJS: Tweak FunctionPrototype::to_string and constructors

The output of FunctionPrototype::to_string is now more in line
with the output in Firefox. The builtin constructors have been
extended to include their function name in the output.

Libraries/LibJS/Runtime/ObjectConstructor.cpp

@@ -35,6 +35,7 @@
 namespace JS {
 
 ObjectConstructor::ObjectConstructor()
+    : NativeFunction("Object")
 {
     put("prototype", interpreter().object_prototype());