Prior to this, ToInt32Constant only matched Int64Constant nodes within
the int32_t range, but did not match actual Int32Constant nodes.

Change-Id: I4e67ea57f53f3b1d4b1f2b27f11ebdeffb2bf357
Reviewed-on: https://chromium-review.googlesource.com/1012022Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52590}