Implemented GetSample like POSIX backtrace()

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 2096efd4afdb8c8b7b6994b0614b09e1b290d64f..f0fd43f4efc83db0d18fdbaae7cbbd38b34fdfc9 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6691,6 +6691,13 @@ void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
 }
 
 
+int Isolate::GetSample(const RegisterState& state,
+                       void** buffer, unsigned int depth) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  return i::Sampler::GetSample(isolate, state, buffer, depth);
+}
+
+
 void Isolate::SetEventLogger(LogEventCallback that) {
   // Do not overwrite the event logger if we want to log explicitly.
   if (i::FLAG_log_timer_events) return;