Add spec for deleting Buffer global in preload

spec/fixtures/module/delete-buffer.js

@@ -0,0 +1,11 @@
+const path = require('path')
+const {remote} = require('electron')
+const {Buffer} = window
+
+delete window.Buffer
+delete global.Buffer
+
+// Test that remote.js doesn't use Buffer global
+remote.require(path.join(__dirname, 'print_name.js')).echo(new Buffer('bar'))
+
+window.test = new Buffer('buffer')