Finally - cheap WiFi?

functionality is built-in (in low level implementation) and does not need to be required("ModuleName");

No, it still needs to be required - there was a regression in a few versions that meant that it didn't, but that's fixed in the newer versions.

I just tried with the binary linked above - specifically http://www.espruino.com/binaries/espruino_1v73_espruino_1r3_esp8266.bin (the forum re-writes links) and it does work. Maybe when you pasted in the URL you then clicked the normal Flash Firmware button and not the Advanced Flash Firmware button?