[turbofan] make LifetimePostion comparable

[turbofan] make LifetimePostion comparable

BUG=

Committed: https://crrev.com/a1528ec0b8fcd37e46ece863025d7210b49117e3
Cr-Commit-Position: refs/heads/master@{#28030}

[Sven Panne, 2015-04-23 12:27:50]

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

[Sven Panne, 2015-04-23 12:27:50]

The CQ bit was checked by svenpanne@chromium.org

[Sven Panne, 2015-04-23 12:27:51]

lgtm

[commit-bot: I haz the power, 2015-04-23 12:28:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1087133004/1

[commit-bot: I haz the power, 2015-04-23 12:36:49]

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

[commit-bot: I haz the power, 2015-04-23 12:36:50]

Try jobs failed on following builders:
  v8_linux_arm64_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_arm64_rel/builds/5097)
  v8_linux_mipsel_compile_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_mipsel_compile_rel...)

[dcarney, 2015-04-23 12:43:42]

The CQ bit was checked by dcarney@chromium.org

[dcarney, 2015-04-23 12:43:43]

The patchset sent to the CQ was uploaded after l-g-t-m from
svenpanne@chromium.org
Link to the patchset: https://codereview.chromium.org/1087133004/#ps20001
(title: " ")

[commit-bot: I haz the power, 2015-04-23 12:43:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1087133004/20001

[commit-bot: I haz the power, 2015-04-23 13:05:55]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-23 13:06:05]

Patchset 2 (id:??) landed as
https://crrev.com/a1528ec0b8fcd37e46ece863025d7210b49117e3
Cr-Commit-Position: refs/heads/master@{#28030}