If the profiler is started via the API and not stopped, V8 will
 intermittently crash during isolate teardown.

The fix is to run the DeleteAllProfiles function in Isolate::Deinit()
 if cpu_profiler_ still exists.

https://groups.google.com/forum/#!topic/v8-dev/WsIlpbaD4mo

TEST= Run in debug mode, if you start a profile and don't stop it,
 this assert should fail:

  Fatal error in ../src/profiler/cpu-profiler.cc, line 414
  Check failed: !is_profiling_.

Review URL: https://codereview.chromium.org/1526253005

Cr-Commit-Position: refs/heads/master@{#32953}