.gitignore mojo .xml files generated by VS2010 gyp.

NOTRY=True

Review URL: https://codereview.chromium.org/95283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237832 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237832