that's weird,i tried it on my phone and the unlock using gmail account only showed when using a pattern,your best bet is to perform a factory reset without the need to unlock the phone try this:
1-Turn off the phone.
2-Press and hold down Volume Up + Home + Power buttons at the same time.
3-Release all buttons when you see the galaxy s 2 Logo.
4-you will be in recovery mode now
5-use volume up/down to select to wipe data/factory reset
6-press the Home button to confirm you selection
7-select "Yes" using the same way.
8-the phone will begin a factory reset now.
9-select "reboot system now" the same way too when factory reset finishes.
this will perform a factory reset to the phone and will remove the lock (all data will be lost)
(the recovery would look like that)