src: fix GetCpuProfiler() deprecation warning

Refs: nodejs/node-v8#46

PR-URL: nodejs/node#19989
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
(cherry picked from commit fbe6b85)

src/env.cc

@@ -95,12 +95,12 @@ void Environment::Start(int argc,
 void Environment::StartProfilerIdleNotifier() {
   uv_prepare_start(&idle_prepare_handle_, [](uv_prepare_t* handle) {
     Environment* env = ContainerOf(&Environment::idle_prepare_handle_, handle);
-    env->isolate()->GetCpuProfiler()->SetIdle(true);
+    env->isolate()->SetIdle(true);
   });
 
   uv_check_start(&idle_check_handle_, [](uv_check_t* handle) {
     Environment* env = ContainerOf(&Environment::idle_check_handle_, handle);
-    env->isolate()->GetCpuProfiler()->SetIdle(false);
+    env->isolate()->SetIdle(false);
   });
 }