Remove a workaround on Electron. See mozilla/pdf.js#12085

Author: tamuratak

src/providers/preview/pdfrenderer_worker.ts

@@ -1,8 +1,3 @@
-// We have to remove `process.versions.electron` to work around a bug of PDF.js.
-// With `process.versions.electron`, PDF.js misinterprets the context of the runtime as
-// the renderer of the browser.
-delete (process.versions as any).electron
-
 import * as domstubs from '@tamuratak/domstubs'
 import * as fs from 'fs'
 import * as path from 'path'