This fixes the self-healing mechanism for closures in the interpreter
entry trampoline not that bytecode can be preserved even when baseline
code is already available.

R=rmcilroy@chromium.org
TEST=cctest/test-compiler/IgnitionEntryTrampolineSelfHealing
BUG=chromium:638225

Review-Url: https://codereview.chromium.org/2257143002
Cr-Commit-Position: refs/heads/master@{#38747}