Add parallel recompilation time to histogram and plot execution pause times.

src/optimizing-compiler-thread.cc

Index: src/optimizing-compiler-thread.cc
diff --git a/src/optimizing-compiler-thread.cc b/src/optimizing-compiler-thread.cc
index 48ee12c680b33b8692c63755cc80bed3ca3bc5dd..1c5bd65b3107dbc7e1c7da144b9ddc0215fd8962 100644
--- a/src/optimizing-compiler-thread.cc
+++ b/src/optimizing-compiler-thread.cc
@@ -48,6 +48,7 @@ void OptimizingCompilerThread::Run() {
 
   while (true) {
     input_queue_semaphore_->Wait();
+    HistogramTimerScope timer(isolate_->counters()->recompile_parallel());
     if (Acquire_Load(&stop_thread_)) {
       stop_semaphore_->Signal();
       if (FLAG_trace_parallel_recompilation) {