Fix deoptimization of context.

Fix deoptimization of context.

We need to handle the case where the context was removed by dead code
elimination. In that case, we just use the context from the activation
(or from the inlined function if we are inlined).

For reference, here is the CL that introduced the bug: https://codereview.chromium.org/522873002

BUG=410556
LOG=N
R=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=23699

[Jarin, 2014-09-04 12:20:36]

jarin@chromium.org changed reviewers:
+ mstarzinger@chromium.org

[Jarin, 2014-09-04 12:27:54]

Could you take a look, please?

Unfortunately, the clusterfuzz repro ends up in an infinite loop, so I cannot
use it as a regression test (and I did not find a way to make it terminate
without breaking the repro).

[Michael Starzinger, 2014-09-04 14:51:37]

LGTM.

[Jarin, 2014-09-04 14:53:02]

Committed patchset #4 (id:60001) manually as 23699 (presubmit successful).