I try to building V8:
Here you written:
"Otherwise (e.g. on Windows), you need to get GYP manually. From the root
of your V8 checkout, run:
svn co http://gyp.googlecode.com/svn/trunk build/gyp".
Please use the mailing list for questions, not the bug tracker.
There is no manual downloading involved. You need to install Subversion.
When you have that, you can run exactly the command provided in the Wiki
(from the root of your V8 checkout):