Unobscurified OFStream.

Unobscurified OFStream.

Use simple HAS-A relationship instead of obscure multiple inheritance.
In theory, UBSan should be totally happy with this, but it still isn't.
This seems to be a bug in UBSan, see e.g.
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2014-December/040225.html

BUG=chromium:448102
LOG=y

Committed: https://crrev.com/327d4a7cde4bf16148b16c71ef467938027c2b49
Cr-Commit-Position: refs/heads/master@{#26139}

[Sven Panne, 2015-01-19 12:24:38]

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

[Benedikt Meurer, 2015-01-19 12:25:56]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2015-01-19 12:25:57]

lgtm

[commit-bot: I haz the power, 2015-01-19 12:26:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/859773002/20001

[Sven Panne, 2015-01-19 12:49:21]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2015-01-19 12:49:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/859773002/40001

[commit-bot: I haz the power, 2015-01-19 13:54:27]

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

[commit-bot: I haz the power, 2015-01-19 13:54:28]

Try jobs failed on following builders:
  v8_win_rel on tryserver.v8
(http://build.chromium.org/p/tryserver.v8/builders/v8_win_rel/builds/2376)

[Sven Panne, 2015-01-19 14:14:25]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2015-01-19 14:14:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/859773002/60001

[commit-bot: I haz the power, 2015-01-19 14:41:43]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2015-01-19 14:41:55]

Patchset 4 (id:??) landed as
https://crrev.com/327d4a7cde4bf16148b16c71ef467938027c2b49
Cr-Commit-Position: refs/heads/master@{#26139}