Karma should start a new browser instance when disconnected by a SyntaxError

### Expected behaviour
I would expect that karma would close the current connection and automatically launch another browser instance when it sees another change in the files that it is watching.
```shell
HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
Uncaught SyntaxError: Unexpected identifier
at event_sequencing.js:52

HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 SUCCESS (0 secs / 0 secs)
HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 5 of 5 SUCCESS (0.012 secs / 0.005 secs)
12 11 2017 08:26:17.933:INFO [watcher]: Changed file "/Users/williamrusnack/Documents/event_sequencing/test.js".
```

### Actual behaviour
Karma instead continues to try and connect to the disconnect browser session when it knows that it has lost the connection.

```shell
HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
Uncaught SyntaxError: Unexpected identifier
at event_sequencing.js:52

HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 SUCCESS (0 secs / 0 secs)
HeadlessChrome 0.0.0 (Mac OS X 10.11.6) ERROR
Disconnected, because no message in 10000 ms.
HeadlessChrome 0.0.0 (Mac OS X 10.11.6): Executed 0 of 5 DISCONNECTED (10.005 secs / 0 secs)
12 11 2017 08:44:02.222:INFO [watcher]: Changed file "/Users/williamrusnack/Documents/event_sequencing/test.js".
12 11 2017 08:44:02.480:WARN [karma]: No captured browser, open http://localhost:9876/
```

### Environment Details

HeadlessChrome 0.0.0 (Mac OS X 10.11.6)
Karma version: 1.7.1

### Steps to reproduce the behaviour
Include any syntax error in the javascript test file or the file to be tested that causes the browser to disconnect.