Translate AST to Hydrogen missing position

Translate AST to Hydrogen missing position

This patch translates RelocInfo::kNoPosition to SourcePosition::Unknown()
in constructing the Hydrogen graph from the parser's output. The translation
is done to increase the flexibility of the parser to desugar more things
that don't have natural locations.

R=bmeurer@chromium.org
BUG=v8:4377
LOG=N

Committed: https://crrev.com/032a35ffb6d625c9a0639c3afd54181938ac49a3
Cr-Commit-Position: refs/heads/master@{#30337}

[Dan Ehrenberg, 2015-08-22 02:01:46]

The CQ bit was checked by littledan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-22 02:01:59]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313443002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313443002/1

[commit-bot: I haz the power, 2015-08-22 02:26:09]

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

[commit-bot: I haz the power, 2015-08-22 02:26:10]

Dry run: This issue passed the CQ dry run.

[Benedikt Meurer, 2015-08-22 06:59:01]

lgtm

[Dan Ehrenberg, 2015-08-24 16:55:54]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-08-24 16:56:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1313443002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1313443002/1

[commit-bot: I haz the power, 2015-08-24 17:18:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-24 17:19:03]

Patchset 1 (id:??) landed as
https://crrev.com/032a35ffb6d625c9a0639c3afd54181938ac49a3
Cr-Commit-Position: refs/heads/master@{#30337}