Add basic C++ implementation of CPU profiler.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 446a614c82f9af0ec8e2147c8b0878aa3f2580da..0fe24579b5d646712b4c6b442013908e5b15084e 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -5731,11 +5731,11 @@ static inline void DateYMDFromTimeSlow(int date,
   bool is_leap = (!yd1 || yd2) && !yd3;
 
   ASSERT(date >= -1);
-  ASSERT(is_leap || date >= 0);
-  ASSERT(date < 365 || is_leap && date < 366);
-  ASSERT(is_leap == (year % 4 == 0 && (year % 100 || (year % 400 == 0))));
-  ASSERT(is_leap || MakeDay(year, 0, 1) + date == save_date);
-  ASSERT(!is_leap || MakeDay(year, 0, 1) + date + 1 == save_date);
+  ASSERT(is_leap || (date >= 0));
+  ASSERT((date < 365) || (is_leap && (date < 366)));
+  ASSERT(is_leap == ((year % 4 == 0) && (year % 100 || (year % 400 == 0))));
+  ASSERT(is_leap || ((MakeDay(year, 0, 1) + date) == save_date));
+  ASSERT(!is_leap || ((MakeDay(year, 0, 1) + date + 1) == save_date));
 
   if (is_leap) {
     day = kDayInYear[2*365 + 1 + date];