Unify memory optimization modes and flags.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 1fd09ccf84e926019a1c9ecf20b451cfcdf1f8be..63688dbd48c9c5787ad1f250579af41bf69127a8 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -7858,13 +7858,13 @@ int Isolate::ContextDisposedNotification(bool dependant_context) {
 
 void Isolate::IsolateInForegroundNotification() {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  return isolate->heap()->SetOptimizeForLatency();
+  return isolate->IsolateInForegroundNotification();
 }
 
 
 void Isolate::IsolateInBackgroundNotification() {
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
-  return isolate->heap()->SetOptimizeForMemoryUsage();
+  return isolate->IsolateInBackgroundNotification();
 }
 
 void Isolate::MemoryPressureNotification(MemoryPressureLevel level) {