Enable the experimental support in escape analysis to deal with
constant-foldable CheckMaps nodes and remove them from the effect
chain w/o blocking the scalar replacement of the object.

BUG=v8:4586,v8:5267
R=tebbi@chromium.org

Review-Url: https://codereview.chromium.org/2964473002
Cr-Commit-Position: refs/heads/master@{#46311}