Embed store callback in handler via weak cell.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index 620f5724d22faf2a0f81546bce9f825c1b00ebff..93f33cf663f0b7ecee75a53f816f056dd307e987 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -1690,8 +1690,7 @@ Handle<Code> StoreIC::CompileHandler(LookupIterator* lookup,
           break;
         }
         NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
-        return compiler.CompileStoreCallback(receiver, lookup->name(),
-                                             lookup->GetAccessorIndex());
+        return compiler.CompileStoreCallback(receiver, lookup->name(), info);
       } else if (accessors->IsAccessorPair()) {
         Handle<Object> setter(Handle<AccessorPair>::cast(accessors)->setter(),
                               isolate());
@@ -2763,14 +2762,16 @@ RUNTIME_FUNCTION(ToBooleanIC_Miss) {
 RUNTIME_FUNCTION(StoreCallbackProperty) {
   Handle<JSObject> receiver = args.at<JSObject>(0);
   Handle<JSObject> holder = args.at<JSObject>(1);
-  Handle<Smi> accessor_index = args.at<Smi>(2);
+  Handle<HeapObject> callback_or_cell = args.at<HeapObject>(2);
   Handle<Name> name = args.at<Name>(3);
   Handle<Object> value = args.at<Object>(4);
   HandleScope scope(isolate);
 
-  Handle<ExecutableAccessorInfo> callback(ExecutableAccessorInfo::cast(
-      holder->map()->instance_descriptors()->GetCallbacksObject(
-          accessor_index->value())));
+  Handle<ExecutableAccessorInfo> callback(
+      callback_or_cell->IsWeakCell()
+          ? ExecutableAccessorInfo::cast(
+                WeakCell::cast(*callback_or_cell)->value())
+          : ExecutableAccessorInfo::cast(*callback_or_cell));
 
   DCHECK(callback->IsCompatibleReceiver(*receiver));