Updated the files.

my-app/node_modules/karma/lib/emitter_wrapper.js

@@ -0,0 +1,33 @@
+'use strict'
+
+class EmitterWrapper {
+  constructor (emitter) {
+    this.listeners = {}
+    this.emitter = emitter
+  }
+
+  addListener (event, listener) {
+    this.emitter.addListener(event, listener)
+    this.listeners[event] = this.listeners[event] || []
+    this.listeners[event].push(listener)
+    return this
+  }
+
+  on (event, listener) {
+    return this.addListener(event, listener)
+  }
+
+  removeAllListeners (event) {
+    const events = event ? [event] : Object.keys(this.listeners)
+    events.forEach((event) => {
+      this.listeners[event].forEach((listener) => {
+        this.emitter.removeListener(event, listener)
+      })
+      delete this.listeners[event]
+    })
+
+    return this
+  }
+}
+
+module.exports = EmitterWrapper