Return MaybeHandle from Object::ToSmi.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index 7df25a0b104df009df77d13d913f4526403bf761..fc5b494e23d4e9805bd2fdc65aee3bc742770062 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -1629,9 +1629,8 @@ bool IsOutOfBoundsAccess(Handle<JSObject> receiver,
 KeyedAccessStoreMode KeyedStoreIC::GetStoreMode(Handle<JSObject> receiver,
                                                 Handle<Object> key,
                                                 Handle<Object> value) {
-  Handle<Object> smi_key = Object::ToSmi(isolate(), key);
-  ASSERT(!smi_key.is_null() && smi_key->IsSmi());
-  int index = Handle<Smi>::cast(smi_key)->value();
+  Handle<Smi> smi_key = Object::ToSmi(isolate(), key).ToHandleChecked();
+  int index = smi_key->value();
   bool oob_access = IsOutOfBoundsAccess(receiver, index);
   // Don't consider this a growing store if the store would send the receiver to
   // dictionary mode.