Fix a few issues breaking cctest/test-lockers/Regress1433:

Fix a few issues breaking cctest/test-lockers/Regress1433:

o The thread local state in an isolate has to be initialized before
  it's used.
o v8::Locker was incorrectly tracking whether it's the topmost one.
o Waking the profiler thread on shutdown should not leave the
  semaphore counter in an inconsitent state.

R=fschneider@chromium.org
BUG=v8:1522
TEST=cctest/test-lockers/Regress1433

Review URL: http://codereview.chromium.org/7309013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8537 ce2b1a6d-e550-0410-aec6-3dcde31c8c00