[counter] Properly measure own-time of runtime counters.

src/arguments.h

Index: src/arguments.h
diff --git a/src/arguments.h b/src/arguments.h
index 28815c158b96098285d72a5e2c5bf4909041e9dd..cba1b439958c993ea50732e76946a8fbf04057f6 100644
--- a/src/arguments.h
+++ b/src/arguments.h
@@ -271,28 +271,23 @@ double ClobberDoubleRegisters(double x1, double x2, double x3, double x4);
 #define CLOBBER_DOUBLE_REGISTERS()
 #endif
 
-#define RUNTIME_FUNCTION_RETURNS_TYPE(Type, Name)                         \
-  static INLINE(Type __RT_impl_##Name(Arguments args, Isolate* isolate)); \
-  Type Name(int args_length, Object** args_object, Isolate* isolate) {    \
-    CLOBBER_DOUBLE_REGISTERS();                                           \
-    RuntimeCallStats* stats = isolate->counters()->runtime_call_stats();  \
-    stats->Count_##Name++;                                                \
-    base::ElapsedTimer timer;                                             \
-    bool timing = false;                                                  \
-    if (FLAG_runtime_call_stats && !stats->in_runtime_call) {             \
-      stats->in_runtime_call = true;                                      \
-      timing = true;                                                      \
-      timer.Start();                                                      \
-    }                                                                     \
-    Arguments args(args_length, args_object);                             \
-    Type value = __RT_impl_##Name(args, isolate);                         \
-    if (timing) {                                                         \
-      stats->in_runtime_call = false;                                     \
-      isolate->counters()->runtime_call_stats()->Time_##Name +=           \
-          timer.Elapsed();                                                \
-    }                                                                     \
-    return value;                                                         \
-  }                                                                       \
+#define RUNTIME_FUNCTION_RETURNS_TYPE(Type, Name)                          \
+  static INLINE(Type __RT_impl_##Name(Arguments args, Isolate* isolate));  \
+  Type Name(int args_length, Object** args_object, Isolate* isolate) {     \
+    CLOBBER_DOUBLE_REGISTERS();                                            \
+    base::ElapsedTimer timer;                                              \
+    if (FLAG_runtime_call_stats) {                                         \
+      RuntimeCallStats* stats = isolate->counters()->runtime_call_stats(); \
+      stats->Enter(&stats->Name);                                          \
+      timer.Start();                                                       \
+    }                                                                      \
+    Arguments args(args_length, args_object);                              \
+    Type value = __RT_impl_##Name(args, isolate);                          \
+    if (FLAG_runtime_call_stats) {                                         \
+      isolate->counters()->runtime_call_stats()->Leave(timer.Elapsed());   \
+    }                                                                      \
+    return value;                                                          \
+  }                                                                        \
   static Type __RT_impl_##Name(Arguments args, Isolate* isolate)
 
 #define RUNTIME_FUNCTION(Name) RUNTIME_FUNCTION_RETURNS_TYPE(Object*, Name)