Add memory pressure notification API

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 8c8f5df13714e2f73a71967c25a4651bf8830b61..dea23a44f3df6e8e23496002d3bf913b48bd6c03 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -7657,6 +7657,11 @@ void Isolate::IsolateInBackgroundNotification() {
   return isolate->heap()->SetOptimizeForMemoryUsage();
 }
 
+void Isolate::MemoryPressureNotification(MemoryPressureLevel level) {
+  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
+  return isolate->heap()->MemoryPressureNotification(level,
+                                                     Locker::IsLocked(this));
+}
 
 void Isolate::SetJitCodeEventHandler(JitCodeEventOptions options,
                                      JitCodeEventHandler event_handler) {