I linked my account by using an intercepting proxy and manually manipulating the OAuth flow. Looks like it's an imgur issue:
Imgur responds the webkit client with a 302 for accounts.google.com:
https://accounts.google.com/o/oauth2/auth?scope=https://www.googleapis.com/auth/userinfo.email%20https://www.googleapis.com/auth/plus.login&state=http://api.imgur.com/oauth2/authorize?client_id=09119b67d9cb8e2&response_type=token&redirect_uri=https://imgur.com/signin/google_plus_callback&response_type=code&client_id={redacted}The problem is that this causes the flow to break down:
state=http://api.imgur.com/oauth2/authorize?client_id=09119b67d9cb8e2&response_type=tokenRemoving the client_id from the state parameter allows the flow to proceed:
https://accounts.google.com/o/oauth2/auth?scope=https://www.googleapis.com/auth/userinfo.email%20https://www.googleapis.com/auth/plus.login&state=http://api.imgur.com/oauth2/authorize?response_type=token&redirect_uri=https://imgur.com/signin/google_plus_callback&response_type=code&client_id={redacted}The OAuth flow proceeds on Google's side, allowing me to login. Then it redirects me back to imgur, but without the client_id in the response token, which causes webkit to go into a recursive loop that concatenates response_type=token a gazillion times over. I can finish off the flow by manually issuing the request that imgur is expecting:
GET /oauth2/authorize?response_type=token&client_id=09119b67d9cb8e2
Hopefully that should help you with the fix. Good luck!