JSFunctions should no longer be materialized on deopt, and the code doing
the materialization doesn't keep track of clearing the optimized code slot
if the function is marked for deopt, so just remove it.

BUG=chromium:718891

Change-Id: I8a1abfd2a1b810017c06fa6f889a85b428cb9dbd
Reviewed-on: https://chromium-review.googlesource.com/498628Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45338}