ReduceJSStoreDataPropertyInLiteral should not reduce the monomorphic
case if the map got deleted. This has been fixed before in the context
of a larger commit, which was reverted.

R=adamk@chromium.org, mvstanton@chromium.org, bmeurer@chromium.org

BUG=v8:5873

Review-Url: https://codereview.chromium.org/2644733007
Cr-Commit-Position: refs/heads/master@{#42548}