remove longstanding race condition in analyzer.py
remove longstanding race condition in analyzer.py

We were blocking the backing thread to *_async() methods in the
Sublime Text api and causing intermittent issues, including
deadlocks.

guillermooo/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo/dart-sublime-bundle,guillermooo-forks/dart-sublime-bundle