Activation tear-off neglects to copy the callee and scope chain, leading to crashes...

Activation tear-off neglects to copy the callee and scope chain, leading to crashes if we
try to create an arguments object from the activation
https://bugs.webkit.org/show_bug.cgi?id=82947
<rdar://problem/11058598>

Reviewed by Gavin Barraclough.

We now copy the entire call frame header just to be sure. This is mostly perf-netural,
except for a 3.7% slow-down in V8/earley.

* runtime/JSActivation.cpp:
(JSC::JSActivation::visitChildren):
* runtime/JSActivation.h:
(JSC::JSActivation::tearOff):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@112947 268f45cc-cd09-0410-ab3c-d52691b4dbfc