Make GetDebugContext a bit more robust.

Make GetDebugContext a bit more robust.

Perhaps we should throw an exception and/or change our external API to
use a MaybeLocal, but that would be a bigger change. For now, we just
return undefined when something goes wrong with the DebugContext,
which is good enough to avoid crashing.

BUG=chromium:474538
LOG=y

Committed: https://crrev.com/18455418253cf62a32f6adcd546db9021817c0ca
Cr-Commit-Position: refs/heads/master@{#27650}

[Sven Panne, 2015-04-08 07:34:32]

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

[Yang, 2015-04-08 08:02:18]

On 2015/04/08 07:34:33, Sven Panne wrote:

LGTM. Maybe a test case?

[Sven Panne, 2015-04-08 09:08:04]

On 2015/04/08 08:02:18, Yang wrote:
> On 2015/04/08 07:34:33, Sven Panne wrote:
> 
> LGTM. Maybe a test case?

The problem with a test case would be that it will either:

   a) test nothing because the stack limit will be too high

   b) crash randomly in an architecture-dependent way because we hit some other
limit during e.g. bootstrapping

So I think it's not worth the trouble.

[Sven Panne, 2015-04-08 09:08:20]

The CQ bit was checked by svenpanne@chromium.org

[commit-bot: I haz the power, 2015-04-08 09:08:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1065213002/1

[commit-bot: I haz the power, 2015-04-08 09:10:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-08 09:10:27]

Patchset 1 (id:??) landed as
https://crrev.com/18455418253cf62a32f6adcd546db9021817c0ca
Cr-Commit-Position: refs/heads/master@{#27650}