HTML5 localhost check

Something like this for mock.lua 

```
local info = sys.get_sys_info()

if info.system_name == "HTML5" then
	local domain = html5.run("window.location.hostname")
	if domain == "localhost" then
		fbinstant = nil
	end
end


if fbinstant then return end
fbinstant = {
	mock = true
}

...
```