[api] Do not force external GCs when only trying to synchronously process phantom callbacks

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 6864 matching lines @@
   ENTER_V8(internal_isolate);
   i::Handle<i::Object> result = internal_isolate->factory()->NewNumber(value);
   return Utils::IntegerToLocal(result);
 }
 
 
 void Isolate::CollectAllGarbage(const char* gc_reason) {
   i::Heap* heap = reinterpret_cast<i::Isolate*>(this)->heap();
   if (heap->incremental_marking()->IsStopped()) {
     if (heap->incremental_marking()->CanBeActivated()) {
-      heap->StartIncrementalMarking(i::Heap::kNoGCFlags, kGCCallbackFlagForced,
-                                    gc_reason);
+      heap->StartIncrementalMarking(
+          i::Heap::kNoGCFlags,
+          kGCCallbackFlagSynchronousPhantomCallbackProcessing, gc_reason);
     } else {
-      heap->CollectAllGarbage(i::Heap::kNoGCFlags, gc_reason,
-                              kGCCallbackFlagForced);
+      heap->CollectAllGarbage(
+          i::Heap::kNoGCFlags, gc_reason,
+          kGCCallbackFlagSynchronousPhantomCallbackProcessing);
     }
   } else {
     // Incremental marking is turned on an has already been started.
 
     // TODO(mlippautz): Compute the time slice for incremental marking based on
     // memory pressure.
     double deadline = heap->MonotonicallyIncreasingTimeInMs() +
                       i::FLAG_external_allocation_limit_incremental_time;
     heap->AdvanceIncrementalMarking(
         0, deadline, i::IncrementalMarking::StepActions(
@@ skipping 1518 matching lines @@
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 }  // namespace internal
 }  // namespace v8