[turbofan] Cleanup Graph and related classes.

[turbofan] Cleanup Graph and related classes.

- Move NodeMarker to its own file, and introduce a non
  templatized base class.
- Cleanup the include hell.
- Sanitize the Node construction methods now that we
  got rid of that GenericNode/GenericGraph stuff.
- Protect against NodeId overflow in Graph.
- Various minor cleanups.

TEST=cctest,mjsunit,unittests

Committed: https://crrev.com/e53845d41cc82f681e04c9ff2c1894f42939a292
Cr-Commit-Position: refs/heads/master@{#25977}

[Benedikt Meurer, 2015-01-07 13:21:35]

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

[Benedikt Meurer, 2015-01-07 13:21:36]

PTAL

[dcarney, 2015-01-07 13:26:23]

lgtm

[dcarney, 2015-01-07 13:26:40]

The CQ bit was checked by dcarney@chromium.org

[Benedikt Meurer, 2015-01-07 13:26:57]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-01-07 13:27:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/838783002/20001

[commit-bot: I haz the power, 2015-01-07 14:42:44]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-07 14:42:56]

Patchset 2 (id:??) landed as
https://crrev.com/e53845d41cc82f681e04c9ff2c1894f42939a292
Cr-Commit-Position: refs/heads/master@{#25977}