[heap] Avoid overzealous inclusion of heap internal headers.

[heap] Avoid overzealous inclusion of heap internal headers.

This is a first step towards constraining down the heap interface to
just the heap.h file. Note that many includes still leak through that
file to the global "src" directory, but there now is a single place
controlling which declarations leak that way. Especially inclusion of
inline header files within "heap" has been limited drastically.

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

Committed: https://crrev.com/65c8ecc65ec8a6a95b7a1fdb96499dd1fbcd21aa
Cr-Commit-Position: refs/heads/master@{#30092}

[Hannes Payer (out of office), 2015-08-10 16:04:13]

This is great! LGTM!

[Michael Lippautz, 2015-08-10 16:29:33]

lgtm

[Michael Starzinger, 2015-08-10 16:30:30]

The CQ bit was checked by mstarzinger@chromium.org

[commit-bot: I haz the power, 2015-08-10 16:30:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1281233003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1281233003/1

[commit-bot: I haz the power, 2015-08-10 16:32:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-10 16:32:37]

Patchset 1 (id:??) landed as
https://crrev.com/65c8ecc65ec8a6a95b7a1fdb96499dd1fbcd21aa
Cr-Commit-Position: refs/heads/master@{#30092}