These are happening more often. Getting a screen shot off to WGT is important, but not as important as getting on with the game.
This probably won't work all the time, but I've successfully gotten back to game on a few occasions. It seems that many times, the "Continue' screen is still there, just hidden by the obnoxious ad.
Move mouse cursor to lower right where 'Continue' button resides. If it turns to the select (pointing hand for most) cursor. Click.
On one occasion, I hit the WGT 'ad' panel, which opened another Chrome tab. When I came back to the game window, the normal 'Continue' screen was there, and I was able to finish the game.
It's possible that the 'Stats' button, upper rightish, would work too. I haven't tried it.
I'd be interested to hear whether any of these works for others, especially in different browsers.