Compiling webkit on windows : environment variable not found $(PRODUCTION)

I am trying to compile webkit on windows and am running into several errors. One of them is :

The following environment variables were not found: $(PRODUCTION)

Does any开发者_C百科body know what this variable is supposed to map to?

Thanks -M

This warning is normal in the development environment and should not result in any real build errors. You are looking for something more severe.