This adds constant folding support for IntPtrEqual/Word{,32,64}{Equal,NotEqual}

Change-Id: I3afe2b5284baf077f03805d2cf48be33282d7bec
Reviewed-on: https://chromium-review.googlesource.com/1053162
Commit-Queue: Kanghua Yu <kanghua.yu@intel.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53768}