Karma failing on Win10

I am trying to build the DagreD3 lib, however, when it tries to run karma I see...

```
[12:10:59] 'core-js:test' errored after 4.54 s
[12:10:59] Error: 1
at formatError (C:\Users\...\AppData\Roaming\nvm\v0.12.9\node_modules\gulp\bin\gulp.js:169:10)
at Gulp. (C:\Users\...\AppData\Roaming\nvm\v0.12.9\node_modules\gulp\bin\gulp.js:195:15)
at Gulp.emit (events.js:107:17)
at Gulp.Orchestrator._emitTaskDone (C:\tmp\d2\node_modules\gulp\node_modules\orchestrator\index.js:264:8)
at C:\tmp\d2\node_modules\gulp\node_modules\orchestrator\index.js:275:23
at finish (C:\tmp\d2\node_modules\gulp\node_modules\orchestrator\lib\runTask.js:21:8)
at cb (C:\tmp\d2\node_modules\gulp\node_modules\orchestrator\lib\runTask.js:29:3)
at removeAllListeners (C:\tmp\d2\node_modules\karma\lib\server.js:215:7)
at Server. (C:\tmp\d2\node_modules\karma\lib\server.js:226:9)
at Server.g (events.js:199:16)
```

I can patch the issue by commenting the following in `/karma/lib/server.js`

```
webServer.close(function () {
clearTimeout(closeTimeout)
// removeAllListeners() fixes the issue
})
```

Start by reproducing the Karma failure while building DagreD3 on Windows 10, focusing on the `core-js:test` task and the cleanup path in `/karma/lib/server.js`. Compare the failure with the reported workaround and verify that the Karma run completes without requiring the manual change.

Written by the indexing model from the issue text.