Fixed test memory leaks

Fixed a bunch of memory leaks in tests, including:
 - String traversal test data (now in a zone)
 - Debug message thread (now joined on exit)
 - Threading test threads (now joined on exit)
 - Changed message tests framework to cope with valgrind
Also, fixed a bug where we'd try to delete stack-allocated objects
when tearing down v8.  Good times.

[Søren Thygesen Gjesse, 2009-03-26 10:50:09]

LGTM

Thanks for getting all this right.

http://codereview.chromium.org/53089/diff/1/2
File include/v8.h (right):

http://codereview.chromium.org/53089/diff/1/2#newcode2042
Line 2042: * a process.
Perhaps explain in which cases this is actually necessary.

http://codereview.chromium.org/53089/diff/1/5
File src/debug.cc (right):

http://codereview.chromium.org/53089/diff/1/5#newcode1742
Line 1742: message_thread_->Stop();
Please add { }'s

Why don't you have to delete message_thread_ here to avoid leaking?

http://codereview.chromium.org/53089/diff/1/8
File src/flags.cc (right):

http://codereview.chromium.org/53089/diff/1/8#newcode61
Line 61: bool owns_ptr_;
Comment (or is it obvious)?

http://codereview.chromium.org/53089/diff/1/18
File test/message/testcfg.py (right):

http://codereview.chromium.org/53089/diff/1/18#newcode43
Line 43: 
Please add a comment on why these lines are ignored.

[Christian Plesner Hansen, 2009-03-27 00:24:26]

http://codereview.chromium.org/53089/diff/1/2
File include/v8.h (right):

http://codereview.chromium.org/53089/diff/1/2#newcode2042
Line 2042: * a process.
Done.  I left it out originally because I had no idea what to write but I've put
something general.

http://codereview.chromium.org/53089/diff/1/5
File src/debug.cc (right):

http://codereview.chromium.org/53089/diff/1/5#newcode1742
Line 1742: message_thread_->Stop();
Done.

Technically it's not a leak as long as there's a static variable pointing to it.
 But yes, it might as well be deleted.

http://codereview.chromium.org/53089/diff/1/8
File src/flags.cc (right):

http://codereview.chromium.org/53089/diff/1/8#newcode61
Line 61: bool owns_ptr_;
Done; it wasn't obvious.

http://codereview.chromium.org/53089/diff/1/18
File test/message/testcfg.py (right):

http://codereview.chromium.org/53089/diff/1/18#newcode43
Line 43: 
Done