Fix building errors (move whatwg-fetch to gatsby-browser)

Author: BrianMitchL

gatsby-browser.js

@@ -4,4 +4,8 @@
  * See: https://www.gatsbyjs.org/docs/browser-apis/
  */
 
-// You can delete this file if you're not using it
+import 'whatwg-fetch'
+
+export const onClientEntry = () => {
+  // export an empty module to make sure the import is used
+}

src/components/Meetup.js

@@ -1,7 +1,6 @@
 import React, { Component } from 'react'
 import PropTypes from 'prop-types'
 import format from 'date-fns/format'
-import 'whatwg-fetch'
 import { graphql, StaticQuery } from 'gatsby'
 
 const MeetupDescription = ({ name, time, venue }) => (