make z-index bigger (vuejs#231)

Author: andreiglingeanu

src/backend/highlighter.js

@@ -3,7 +3,7 @@ import { inDoc } from '../util'
 const overlay = document.createElement('div')
 overlay.style.backgroundColor = 'rgba(104, 182, 255, 0.35)'
 overlay.style.position = 'fixed'
-overlay.style.zIndex = '99999'
+overlay.style.zIndex = '99999999999999'
 overlay.style.pointerEvents = 'none'
 
 /**