[turbofan] Remove unnecessary check for prototype map in reducers for Array.

Change-Id: Ib53ebb8372bd952f038edc06166e7d1c8b05abc2
Reviewed-on: https://chromium-review.googlesource.com/1174549
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55182}

src/compiler/js-call-reducer.cc

@@ -977,7 +977,6 @@ bool CanInlineArrayIteratingBuiltin(Isolate* isolate,
                                      isolate);
   return receiver_map->instance_type() == JS_ARRAY_TYPE &&
          IsFastElementsKind(receiver_map->elements_kind()) &&
-         (!receiver_map->is_prototype_map() || receiver_map->is_stable()) &&
          isolate->IsNoElementsProtectorIntact() &&
          isolate->IsAnyInitialArrayPrototype(receiver_prototype);
 }