[heap] No leakage of objects-visiting.h outside of heap.

[heap] No leakage of objects-visiting.h outside of heap.

This prevents the internal objects-visiting.h to be usable outisde of
the "heap" directory. The static object visitation is only usefull
within the GC and is now properly encapsulated.

R=hpayer@chromium.org,mlippautz@chromium.org

Committed: https://crrev.com/a0bc7651aba787426bae456a9217fd80b03b55c5
Cr-Commit-Position: refs/heads/master@{#30716}

[Michael Starzinger, 2015-09-04 12:54:04]

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

[Michael Lippautz, 2015-09-04 13:40:10]

lgtm

[Hannes Payer (out of office), 2015-09-14 09:57:45]

lgtm

[Michael Starzinger, 2015-09-14 12:26:58]

The CQ bit was checked by mstarzinger@chromium.org

[Michael Starzinger, 2015-09-14 12:26:59]

The patchset sent to the CQ was uploaded after l-g-t-m from hpayer@chromium.org,
mlippautz@chromium.org
Link to the patchset: https://codereview.chromium.org/1328003002/#ps20001
(title: "Rebased.")

[commit-bot: I haz the power, 2015-09-14 12:27:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1328003002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1328003002/20001

[commit-bot: I haz the power, 2015-09-14 12:28:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-14 12:28:53]

Patchset 2 (id:??) landed as
https://crrev.com/a0bc7651aba787426bae456a9217fd80b03b55c5
Cr-Commit-Position: refs/heads/master@{#30716}