MSVS compilation fix after r14006

BUG=None

Review URL: https://codereview.chromium.org/12931004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14009 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/log.h

@@ -77,6 +77,7 @@ class Semaphore;
 class Ticker;
 class Isolate;
 class PositionsRecorder;
+class CpuProfiler;
 
 #undef LOG
 #define LOG(isolate, Call)                          \