Make v8 compile on VS2013.
VS2013 contains a number of improvements, most notably the addition of all C99 math functions.
I'm a little bit concerned about the change I had to make in cpu-profiler.cc, but I spent quite a bit of time looking at it and was unable to figure out any rational explanation for the warning. It's possible it's spurious. Since it seems like a useful warning in general though, I chose not to disable globally at the gyp level.
I do think someone with expertise here should probably try to determine if this is a legitimate warning.