Fix gyp settings for builds within Visual Studio.

Fix gyp settings for builds within Visual Studio.

This is landing of a community patch from  Don J. Olmstead, see: http://code.google.com/p/dart/issues/detail?id=4296
Committed: https://code.google.com/p/dart/source/detail?r=10366

[ricow1, 2012-08-08 07:24:43]

CC'ing Peter

[Søren Gjesse, 2012-08-08 07:44:13]

LGTM, but should we mention the author in the commit message?

[ricow1, 2012-08-08 07:49:17]

Yes, we should, added his name to the cl description

[ahe, 2012-08-21 19:54:12]

LGTM