JS Code Hints automatic crash preventer

[dangoor]

This is copied from the card in Trello for tracking in Waffle.

Tern will sometimes spiral out of control on certain JavaScript files. This causes tremendously slowed down performance (because Tern will consume 100% of CPU at those times) and eventually a crash because memory is completely consumed.

We want to automatically stop hinting for these problematic files.

Once we've done this, we can probably remove the line count limit because the problems we see are less likely about number of lines and more likely about the nature of the JS being analyzed.

Criteria

• Detect that a file has caused Tern to enter this state
• Terminate the worker (ideally, if this is not possibly, detect the problem at startup)
• Notify the user that hinting is being turned off for the JS file and suggest that they consider reporting an issue.
• save an exclusion to .brackets.json
• Experiment with removing the LARGE_LINE_COUNT maximum

Related Bugs

This list, at least. There are certainly more:

• Brackets grey screens and crashes when editing JS files
• Mac OSX - Freeze - Grey Screen
• Entire window goes blank
• Brackets crashes
• CPU stays at 100% with specific project

[njx]

Assigning to @dangoor since you're assigned to review the associated PR (and this was showing as unassigned on the Waffle board)