addComponentAsRefTo() error because google_map.js loads a second copy of React

[jedwards1211]

I'm getting this error:
Uncaught Error: Invariant Violation: addComponentAsRefTo(...): Only a ReactOwner can have refs. This usually means that you're trying to add a ref to a component that doesn't have an owner (that is, was not created inside of another component'srendermethod). Try rendering this component inside of a new top-level component which will hold the ref.

Somehow the GoogleMap component was loading a second copy of React. I think it's similar to what these people are seeing:
facebook/react#3320

I had to use the PrefetchPlugin on react to get google-map-react to work. Maybe the rest of my code was loading plain old 'react' and GoogleMap is loading 'react/addons', but in any case I think it would help other developers new to google-map-react to have a note about this.