Revert of Make full GC reduce memory footprint an explicit event in the idle notification handler.

Revert of Make full GC reduce memory footprint an explicit event in the idle notification handler. (patchset #2 id:20001 of https://codereview.chromium.org/1072363002/)

Reason for revert:
[Sheriff] breaks nosnap with timeouts:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20nosnap/builds/2513
http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20nosnap%20-%20shared/builds/6220

Original issue's description:
> Make full GC reduce memory footprint an explicit event in the idle notification handler.
>
> BUG=
>
> Committed: https://crrev.com/845705aa99b6bfa8d264cfda1c3b5f1229802ab5
> Cr-Commit-Position: refs/heads/master@{#27753}

TBR=ulan@chromium.org,rmcilroy@chromium.org,hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/7898475e92e2be05868a5755815732bd11f6a3ca
Cr-Commit-Position: refs/heads/master@{#27755}

[Michael Achenbach, 2015-04-10 18:21:22]

Created Revert of Make full GC reduce memory footprint an explicit event in the
idle notification handler.

[commit-bot: I haz the power, 2015-04-10 18:21:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1081443002/1

[commit-bot: I haz the power, 2015-04-10 18:21:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-10 18:21:57]

Patchset 1 (id:??) landed as
https://crrev.com/7898475e92e2be05868a5755815732bd11f6a3ca
Cr-Commit-Position: refs/heads/master@{#27755}