fix: SPDY fails in node >= 11.1.0 (#1660)

Author: yi-ge

lib/Server.js

@@ -17,7 +17,6 @@ const tls = require('tls');
 const url = require('url');
 const http = require('http');
 const https = require('https');
-const spdy = require('spdy');
 const sockjs = require('sockjs');
 
 const semver = require('semver');
@@ -635,7 +634,12 @@ class Server {
       if (semver.gte(process.version, '10.0.0')) {
         this.listeningApp = https.createServer(options.https, app);
       } else {
-        this.listeningApp = spdy.createServer(options.https, app);
+        /* eslint-disable global-require */
+        // The relevant issues are:
+        // https://github.com/spdy-http2/node-spdy/issues/350
+        // https://github.com/webpack/webpack-dev-server/issues/1592
+        this.listeningApp = require('spdy').createServer(options.https, app);
+        /* eslint-enable global-require */
       }
     } else {
       this.listeningApp = http.createServer(app);