[heap] Fix corner case in optimized code map processing.

[heap] Fix corner case in optimized code map processing.

This fixes a corner case where optimized code could still be reachable
through the optimized code map, even though unoptimized code for any
inlined function might have long been flushed.

R=ulan@chromium.org
TEST=cctest/test-heap/Regress513496
BUG=chromium:513496
LOG=n

Committed: https://crrev.com/aac8ee84affbff5b0516e75340acf5fc417bee80
Cr-Commit-Position: refs/heads/master@{#31857}

[ulan, 2015-11-05 15:52:14]

lgtm!

[Hannes Payer (out of office), 2015-11-05 19:40:00]

hpayer@chromium.org changed reviewers:
+ hpayer@chromium.org

[Hannes Payer (out of office), 2015-11-05 19:40:00]

lgtm!

[Michael Starzinger, 2015-11-06 14:27:34]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2015-11-06 14:27:34]

The patchset sent to the CQ was uploaded after l-g-t-m from ulan@chromium.org,
hpayer@chromium.org
Link to the patchset: https://codereview.chromium.org/1415683011/#ps40001
(title: "Rebased.")

[commit-bot: I haz the power, 2015-11-06 14:27:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415683011/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415683011/40001

[commit-bot: I haz the power, 2015-11-06 14:28:56]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-11-06 14:29:34]

Patchset 3 (id:??) landed as
https://crrev.com/aac8ee84affbff5b0516e75340acf5fc417bee80
Cr-Commit-Position: refs/heads/master@{#31857}