Update, June 2018: It turns out that this script is overkill. (Which is good, because it was unreliable.) You can bypass the captive portal by setting your user agent to that of a mobile device using Chrome DevTools, a user agent switcher, or an equivalent tool.
Short script to bypass the SafeConnect network access control system.
I wrote this because SafeConnect wouldn't let me use ResNet because I didn't have antivirus installed on my work laptop. Except I did have an antivirus client installed, so it was kinda just annoying. The other SafeConnect solutions I tried didn't work so I just wrote my own.