Reland of [counters] adding runtime call timers for GC

src/heap/gc-tracer.h

Index: src/heap/gc-tracer.h
diff --git a/src/heap/gc-tracer.h b/src/heap/gc-tracer.h
index 90ea41027c43f19af461d91bc65d7efc56aedf18..175a8ed5a786d3a9fe206d3ef2a7eca1111847de 100644
--- a/src/heap/gc-tracer.h
+++ b/src/heap/gc-tracer.h
@@ -6,6 +6,7 @@
 #define V8_HEAP_GC_TRACER_H_
 
 #include "src/base/platform/platform.h"
+#include "src/counters.h"
 #include "src/globals.h"
 
 namespace v8 {
@@ -87,7 +88,6 @@
 
 
 enum ScavengeSpeedMode { kForAllObjects, kForSurvivedObjects };
-
 
 // GCTracer collects and prints ONE line after each garbage collector
 // invocation IFF --trace_gc is used.
@@ -152,6 +152,7 @@
     GCTracer* tracer_;
     ScopeId scope_;
     double start_time_;
+    RuntimeCallTimer timer_;
 
     DISALLOW_COPY_AND_ASSIGN(Scope);
   };
@@ -613,6 +614,9 @@
   // Counts how many tracers were started without stopping.
   int start_counter_;
 
+  // Separate timer used for --runtime_call_stats
+  RuntimeCallTimer timer_;
+
   DISALLOW_COPY_AND_ASSIGN(GCTracer);
 };
 }  // namespace internal