[api,heap] Fix external GC callbacks.

src/global-handles.cc

Index: src/global-handles.cc
diff --git a/src/global-handles.cc b/src/global-handles.cc
index fcf896fe5f5b766c409d96836078e34e257d8e3d..befa173767064e871062dcf36e7428fa590404ab 100644
--- a/src/global-handles.cc
+++ b/src/global-handles.cc
@@ -507,7 +507,11 @@ class GlobalHandles::PendingPhantomCallbacksSecondPassTask
   }
 
   void RunInternal() override {
+    isolate_->heap()->CallGCPrologueCallbacks(
+        GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags);
     InvokeSecondPassPhantomCallbacks(&pending_phantom_callbacks_, isolate_);
+    isolate_->heap()->CallGCEpilogueCallbacks(
+        GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags);
   }
 
  private:
@@ -841,7 +845,11 @@ int GlobalHandles::DispatchPendingPhantomCallbacks(
   }
   if (pending_phantom_callbacks_.length() > 0) {
     if (FLAG_optimize_for_size || FLAG_predictable || synchronous_second_pass) {
+      isolate()->heap()->CallGCPrologueCallbacks(
+          GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags);
       InvokeSecondPassPhantomCallbacks(&pending_phantom_callbacks_, isolate());
+      isolate()->heap()->CallGCEpilogueCallbacks(
+          GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags);
     } else {
       auto task = new PendingPhantomCallbacksSecondPassTask(
           &pending_phantom_callbacks_, isolate());