api: Expose initial_array_prototype to public

There is a demand of access to %Array.prototype% in Blink in
order to implement Web IDL observable array type.

Bug: chromium:1201744
Change-Id: I31ca5cd746f3a2eab8bd291741408a1dea17c122
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3194025
Auto-Submit: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77200}

include/v8-template.h

@@ -27,6 +27,7 @@ class Signature;
   F(ArrayProto_forEach, array_for_each_iterator)              \
   F(ArrayProto_keys, array_keys_iterator)                     \
   F(ArrayProto_values, array_values_iterator)                 \
+  F(ArrayPrototype, initial_array_prototype)                  \
   F(AsyncIteratorPrototype, initial_async_iterator_prototype) \
   F(ErrorPrototype, initial_error_prototype)                  \
   F(IteratorPrototype, initial_iterator_prototype)            \