[v14.x] deps: V8: cherry-pick 81181a8ad80a

Original commit message:

    [JSON] Fix GC issue in BuildJsonObject
    We must ensure that the sweeper is not running or has already swept
    mutable_double_buffer. Otherwise the GC can add it to the free list.

    Bug: v8:11837
    Change-Id: Ifd9cf15f1c94f664fd6489c70bb38b59730cdd78
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2928181
    Commit-Queue: Victor Gomes <[email protected]>
    Reviewed-by: Toon Verwaest <[email protected]>
    Reviewed-by: Dominik Inführ <[email protected]>
    Cr-Commit-Position: refs/heads/master@{#74859}

Refs: v8/v8@81181a8

common.gypi

@@ -36,7 +36,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.67',
+    'v8_embedder_string': '-node.68',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/src/heap/heap.cc

@@ -3347,6 +3347,10 @@ void Heap::MakeHeapIterable() {
   mark_compact_collector()->EnsureSweepingCompleted();
 }
 
+void Heap::EnsureSweepingCompleted() {
+  mark_compact_collector()->EnsureSweepingCompleted();
+}
+
 namespace {
 
 double ComputeMutatorUtilizationImpl(double mutator_speed, double gc_speed) {

deps/v8/src/heap/heap.h

@@ -1001,6 +1001,8 @@ class Heap {
       Reservation* reservations, const std::vector<HeapObject>& large_objects,
       const std::vector<Address>& maps);
 
+  void EnsureSweepingCompleted();
+
   IncrementalMarking* incremental_marking() {
     return incremental_marking_.get();
   }

deps/v8/src/json/json-parser.cc

@@ -633,6 +633,11 @@ Handle<Object> JsonParser<Char>::BuildJsonObject(
         DCHECK_EQ(mutable_double_address, end);
       }
 #endif
+      // Before setting the length of mutable_double_buffer back to zero, we
+      // must ensure that the sweeper is not running or has already swept the
+      // object's page. Otherwise the GC can add the contents of
+      // mutable_double_buffer to the free list.
+      isolate()->heap()->EnsureSweepingCompleted();
       mutable_double_buffer->set_length(0);
     }
   }