Resolve race condition in CompilationCacheTable::Put

Resolve race condition with GC in CompilationCacheTable::Put.

The trouble is that the AsHandle method can allocate and thus
invoke GC, which could empty the table while we are updating it.

BUG=chromium:430880
LOG=N
R=verwaest@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=25229

[Jarin, 2014-11-06 13:39:04]

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

[Jarin, 2014-11-06 13:56:55]

Could you take a look, please?

I could upload the clusterfuzz repro case, but it is quite brittle (GC has to
happen at a certain point) and long running, so I think it is not worth it. I
tried to minimize it, but whatever I touch, it stops crashing.

[Toon Verwaest, 2014-11-06 16:00:40]

lgtm

[Jarin, 2014-11-10 05:50:16]

Committed patchset #1 (id:1) manually as 25229 (presubmit successful).