chore: migrate test cases from Chai to Jest

src/emitters/streamed-emitter-browser.ts

@@ -1,12 +0,0 @@
-import { Emitter } from './emitter'
-
-export class StreamedEmitter implements Emitter {
-  public buffer = '';
-  public stream: NodeJS.ReadableStream = null as any
-  constructor () {
-    throw new Error('streaming not supported in browser')
-  }
-  public write: (html: any) => void
-  public error: (err: Error) => void
-  public end: () => void
-}