Fix and re-enable v8 idle notification after commit.

Fix and re-enable v8 idle notification after commit.

For idle times < 1000us, we sent notifications with 0ms. This patch
adds a check for idle_time_in_ms to be non-zero and re-enables the
feature by default.

R=jochen@chromium.org
BUG=414815
Committed: https://crrev.com/5e0a3fde818bfe005bc37100626b188b8d5d7c84
Cr-Commit-Position: refs/heads/master@{#295680}

[ernstm, 2014-09-18 22:52:50]

PTAL

[jochen (gone - plz use gerrit), 2014-09-19 04:01:03]

lgtm.

[jochen (gone - plz use gerrit), 2014-09-19 04:01:05]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2014-09-19 04:01:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/583833002/1

[commit-bot: I haz the power, 2014-09-19 05:07:37]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-09-19 05:07:38]

Try jobs failed on following builders:
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[jochen (gone - plz use gerrit), 2014-09-19 05:27:28]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2014-09-19 05:27:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/583833002/1

[commit-bot: I haz the power, 2014-09-19 06:29:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-09-19 06:29:29]

Try jobs failed on following builders:
  mac_chromium_rel_swarming on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[jochen (gone - plz use gerrit), 2014-09-19 06:33:12]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2014-09-19 06:33:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/583833002/1

[commit-bot: I haz the power, 2014-09-19 08:36:43]

Committed patchset #1 (id:1) as 4bc4491985cd59e4b5719dac75a1d73b35ec1106

[commit-bot: I haz the power, 2014-09-19 08:37:23]

Patchset 1 (id:??) landed as
https://crrev.com/5e0a3fde818bfe005bc37100626b188b8d5d7c84
Cr-Commit-Position: refs/heads/master@{#295680}