The new Smi handler created to handle StoreIC_Slow and
KeyedStoreIC_Slow can get incorrectly assigned to global Objects.
Added an extra Check to avoid that.

Bug: chromium:1002628
Change-Id: I370e617e791792c98fa7b0cbf89ee7458f4e4c68
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1803659Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Suraj Sharma <surshar@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#63813}