Fix typo in header guard of v8-platform.h

TBR=svenpanne@chromium.org
BUG=none
LOG=n

Review URL: https://codereview.chromium.org/76313002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@17879 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8-platform.h

@@ -25,7 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef V8_V8_PLATFROM_H_
+#ifndef V8_V8_PLATFORM_H_
 #define V8_V8_PLATFORM_H_
 
 #include "v8.h"