fix: Use correct config property for parser plugins (#1082)

Author: coreyfarrell

lib/instrumenters/istanbul.js

@@ -5,7 +5,7 @@ const convertSourceMap = require('convert-source-map')
 const mergeSourceMap = require('merge-source-map')
 
 function InstrumenterIstanbul (options) {
-  const plugins = options.parserPlugins
+  const { plugins } = options
   const configPlugins = plugins ? { plugins } : {}
 
   const instrumenter = createInstrumenter(Object.assign({