Revert of Disallow passing a SharedArrayBuffer in the transfer list.

src/value-serializer.cc

Index: src/value-serializer.cc
diff --git a/src/value-serializer.cc b/src/value-serializer.cc
index 55c0ffb0eb29840436c41f622f92d4f37854796c..81301fd55395b4e8d2f356ec9413da6b6425953b 100644
--- a/src/value-serializer.cc
+++ b/src/value-serializer.cc
@@ -110,8 +110,8 @@
   // ObjectReference to one) serialized just before it. This is a quirk arising
   // from the previous stack-based implementation.
   kArrayBufferView = 'V',
-  // Shared array buffer. transferID:uint32_t
-  kSharedArrayBuffer = 'u',
+  // Shared array buffer (transferred). transferID:uint32_t
+  kSharedArrayBufferTransfer = 'u',
   // Compiled WebAssembly module. encodingType:(one-byte tag).
   // If encodingType == 'y' (raw bytes):
   //  wasmWireByteLength:uint32_t, then raw data
@@ -269,7 +269,6 @@
 void ValueSerializer::TransferArrayBuffer(uint32_t transfer_id,
                                           Handle<JSArrayBuffer> array_buffer) {
   DCHECK(!array_buffer_transfer_map_.Find(array_buffer));
-  DCHECK(!array_buffer->is_shared());
   array_buffer_transfer_map_.Set(array_buffer, transfer_id);
 }
 
@@ -443,7 +442,7 @@
     case JS_SET_TYPE:
       return WriteJSSet(Handle<JSSet>::cast(receiver));
     case JS_ARRAY_BUFFER_TYPE:
-      return WriteJSArrayBuffer(Handle<JSArrayBuffer>::cast(receiver));
+      return WriteJSArrayBuffer(JSArrayBuffer::cast(*receiver));
     case JS_TYPED_ARRAY_TYPE:
     case JS_DATA_VIEW_TYPE:
       return WriteJSArrayBufferView(JSArrayBufferView::cast(*receiver));
@@ -725,29 +724,20 @@
   return Just(true);
 }
 
-Maybe<bool> ValueSerializer::WriteJSArrayBuffer(
-    Handle<JSArrayBuffer> array_buffer) {
-  if (array_buffer->is_shared()) {
-    if (!delegate_) {
-      ThrowDataCloneError(MessageTemplate::kDataCloneError, array_buffer);
-      return Nothing<bool>();
-    }
-
-    v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate_);
-    Maybe<uint32_t> index = delegate_->GetSharedArrayBufferId(
-        v8_isolate, Utils::ToLocalShared(array_buffer));
-    RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate_, Nothing<bool>());
-
-    WriteTag(SerializationTag::kSharedArrayBuffer);
-    WriteVarint(index.FromJust());
-    return Just(true);
-  }
-
+Maybe<bool> ValueSerializer::WriteJSArrayBuffer(JSArrayBuffer* array_buffer) {
   uint32_t* transfer_entry = array_buffer_transfer_map_.Find(array_buffer);
   if (transfer_entry) {
-    WriteTag(SerializationTag::kArrayBufferTransfer);
+    WriteTag(array_buffer->is_shared()
+                 ? SerializationTag::kSharedArrayBufferTransfer
+                 : SerializationTag::kArrayBufferTransfer);
     WriteVarint(*transfer_entry);
     return Just(true);
+  }
+
+  if (array_buffer->is_shared()) {
+    ThrowDataCloneError(
+        MessageTemplate::kDataCloneErrorSharedArrayBufferNotTransferred);
+    return Nothing<bool>();
   }
   if (array_buffer->was_neutered()) {
     ThrowDataCloneError(MessageTemplate::kDataCloneErrorNeuteredArrayBuffer);
@@ -755,7 +745,7 @@
   }
   double byte_length = array_buffer->byte_length()->Number();
   if (byte_length > std::numeric_limits<uint32_t>::max()) {
-    ThrowDataCloneError(MessageTemplate::kDataCloneError, array_buffer);
+    ThrowDataCloneError(MessageTemplate::kDataCloneError, handle(array_buffer));
     return Nothing<bool>();
   }
   WriteTag(SerializationTag::kArrayBuffer);
@@ -1115,7 +1105,7 @@
       const bool is_shared = false;
       return ReadTransferredJSArrayBuffer(is_shared);
     }
-    case SerializationTag::kSharedArrayBuffer: {
+    case SerializationTag::kSharedArrayBufferTransfer: {
       const bool is_shared = true;
       return ReadTransferredJSArrayBuffer(is_shared);
     }