Fix a bug in heap profile tracing of closures.

Fix a bug in heap profile tracing of closures.

The heap profile tracers assumed that a closure always closed over a
function context.  This is obviously not true (e.g., function expressions
nested inside catch or with).  This assumption could lead to using a
function's scope info to interpret a catch or with context.

R=vegorov@chromium.org
BUG=v8:2078
TEST=

Committed: https://code.google.com/p/v8/source/detail?r=11348

[Vyacheslav Egorov (Chromium), 2012-04-17 10:41:06]

lgtm