Add TextMate Scopes for eval/package

[jabacchetta]

As documented on StackOverfow, I was able to target all of JavaScript's reserved keywords via TextMate with the exception of two:

1. eval (disallowed in strict)
2. package (unused future keyword)

It's not clear to me whether this is something that needs to be updated in the TextMate grammar or if support just needs to be added in VS Code.

For eval, a support.function.eval.js scope appears to make sense. With package not actually being used yet, I'm not sure what scope that would go under.

[mjbvz]

This issue was moved to microsoft/TypeScript-TmLanguage#634