Fix for bug 351257: type feedback vector initialization issue.

Fix for bug 351257: type feedback vector initialization issue.

The feedback vector is stored in the shared function info, and there
is an effort to reuse it when re-running full code generation as a
prelude to creating optimized code. However we shouldn't reuse the
vector for lazily compiled methods on first compile, as scoping analysis
can change the allocation of vector slots.

BUG=351257
LOG=N
R=danno@chromium.org, bmeuer@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19854

[mvstanton, 2014-03-12 12:57:18]

Hi Benedikt, 
ClusterFuzz found an issue in the type feedback vector implementation. I've
profitably reduced it's test case to a cctest. PTAL, thanks!
--Michael

[mvstanton, 2014-03-12 14:07:04]

Hi DAnno, you might have a look...

[danno, 2014-03-12 14:33:41]

lgtm

[mvstanton, 2014-03-12 15:18:24]

Committed patchset #1 manually as r19854 (presubmit successful).