Port 1c507667

Original Commit Message:

    There is no need for write barriers if the stored value is known to be a
    Smi.

R=clemensb@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: I2b79511b7f2789e6fc95ae5cb349b0f2288822fc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2712787Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72918}