[counters] adding runtime call timers for GC

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index e9b67efbbc230724a16751e8baaeadd877c845fc..7bf65a45760d268421051b5af50baecd15a07752 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1009,6 +1009,8 @@ bool Heap::CollectGarbage(GarbageCollector collector, const char* gc_reason,
       HistogramTimer* gc_type_timer = GCTypeTimer(collector);
       HistogramTimerScope histogram_timer_scope(gc_type_timer);
       TRACE_EVENT0("v8", gc_type_timer->name());
+      RuntimeCallTimerScope timer(

[ulan, 2016/03/23 13:59:56]

Please move this to GcTracer::Start / Stop similar to the scope and guard by the
runtime flag.

+          isolate(), &isolate()->counters()->runtime_call_stats()->GC);
 
       next_gc_likely_to_collect_more =
           PerformGarbageCollection(collector, gc_callback_flags);