Add failing spec for Buffer from preload required module

spec/fixtures/module/preload-node-off-wrapper.js

@@ -0,0 +1,3 @@
+setImmediate(function () {
+  require('./preload-required-module')
+})

spec/fixtures/module/preload-required-module.js

@@ -0,0 +1,5 @@
+try {
+  console.log([typeof process, typeof setImmediate, typeof global, typeof Buffer].join(' '))
+} catch (e) {
+  console.log(e.message)
+}

spec/webview-spec.js

@@ -181,7 +181,7 @@ describe('<webview> tag', function () {
       document.body.appendChild(webview)
     })
 
-    it('preload script can still use "process" and "Buffer" in required modules when nodeintegration is off', function (done) {
+    it('preload script can still use "process" and "Buffer" when nodeintegration is off', function (done) {
       webview.addEventListener('console-message', function (e) {
         assert.equal(e.message, 'object undefined object function')
         done()
@@ -191,6 +191,16 @@ describe('<webview> tag', function () {
       document.body.appendChild(webview)
     })
 
+    it('preload script can require modules that still use "process" and "Buffer"when nodeintegration is off', function (done) {
+      webview.addEventListener('console-message', function (e) {
+        assert.equal(e.message, 'object undefined object function')
+        done()
+      })
+      webview.setAttribute('preload', fixtures + '/module/preload-node-off-wrapper.js')
+      webview.src = 'file://' + fixtures + '/api/blank.html'
+      document.body.appendChild(webview)
+    })
+
     it('receives ipc message in preload script', function (done) {
       var message = 'boom!'
       var listener = function (e) {