Fastpath some spread-call desugaring.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index cafe546191bba737b06692b79d23808ec40feee5..a97118fe211d31fdefe818698ca47d023aaea572 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2950,6 +2950,14 @@ void Isolate::InvalidateStringLengthOverflowProtector() {
   DCHECK(!IsStringLengthOverflowIntact());
 }
 
+void Isolate::InvalidateArrayIteratorProtector() {
+  DCHECK(factory()->array_iterator_protector()->value()->IsSmi());
+  DCHECK(IsArrayIteratorLookupChainIntact());
+  factory()->array_iterator_protector()->set_value(
+      Smi::FromInt(kArrayProtectorInvalid));
+  DCHECK(!IsArrayIteratorLookupChainIntact());
+}
+
 bool Isolate::IsAnyInitialArrayPrototype(Handle<JSArray> array) {
   DisallowHeapAllocation no_gc;
   return IsInAnyContext(*array, Context::INITIAL_ARRAY_PROTOTYPE_INDEX);