Fix lint
Fix lint

Test plan:
 - `npm test`

Auditors: alpert

mcanthony/KaTeX,zhanghuiguoanlige/KaTeX,spicyj/KaTeX,azotova/KaTeX,JetStarBlues/KaTeX,zhanghuiguoanlige/KaTeX,saschatimme/KaTeX,kwangkim/katex-npm-0.7.0-pre,xymostech/KaTeX,kwangkim/KaTeX,azotova/KaTeX,kevinbarabash/KaTeX,kwangkim/katex-npm-0.7.0-pre,gagern/KaTeX,gagern/KaTeX,kevinbarabash/KaTeX,saschatimme/KaTeX,saschatimme/KaTeX,Khan/KaTeX,azotova/KaTeX,kwangkim/katex-npm-0.7.0-pre,saschatimme/KaTeX,frankandrobot/KaTeX,kwangkim/KaTeX,Khan/KaTeX,gagern/KaTeX,zhanghuiguoanlige/KaTeX,crepererum/KaTeX,xymostech/KaTeX,kevinbarabash/KaTeX,mcanthony/KaTeX,Khan/KaTeX,franciscop/KaTeX,mcanthony/KaTeX,frankandrobot/KaTeX,gagern/KaTeX,crepererum/KaTeX,zhanghuiguoanlige/KaTeX,azotova/KaTeX,franciscop/KaTeX,kwangkim/KaTeX,spicyj/KaTeX,frankandrobot/KaTeX,twitwi/KaTeX,JetStarBlues/KaTeX,twitwi/KaTeX,kwangkim/KaTeX,crepererum/KaTeX,kwangkim/KaTeX,JetStarBlues/KaTeX,zhanghuiguoanlige/KaTeX,franciscop/KaTeX,kwangkim/katex-npm-0.7.0-pre,franciscop/KaTeX,twitwi/KaTeX,gagern/KaTeX,twitwi/KaTeX,twitwi/KaTeX,azotova/KaTeX,crepererum/KaTeX,xymostech/KaTeX,frankandrobot/KaTeX,saschatimme/KaTeX,spicyj/KaTeX,JetStarBlues/KaTeX,mcanthony/KaTeX,xymostech/KaTeX,JetStarBlues/KaTeX,kevinbarabash/KaTeX,spicyj/KaTeX,spicyj/KaTeX,kevinbarabash/KaTeX,franciscop/KaTeX,mcanthony/KaTeX,xymostech/KaTeX,kwangkim/katex-npm-0.7.0-pre,crepererum/KaTeX,frankandrobot/KaTeX