variable leak: tabWidth

[aredridel]

When integrating marky 7, I ran into our test suite flagging this leaking into global scope:

The following leaks were detected:tabWidth

[aredridel]

Failing test case in #181

[revin]

oops, that's my fault: https://github.com/revin/markdown-it-expand-tabs/blob/master/index.js#L5-L9 ; I'll fix it ASAP

[revin]

(Where's the 'dependency author is a n00b' label?)

[aredridel]

(Nowhere 'cause we all do this. It's one of the sharp corners of JS)

[revin]

ok I pushed markdown-it-expand-tabs@1.0.10; we semver it in as ^1.0.7 so it should work OOTB now, no?

[revin]

Got a new PR: #186.

[revin]

Fixed by markdown-it-expand-tabs@1.0.10, test implemented here in #186