Switch from PhantomJS to Headless Chrome

[uglow]

See:

• https://groups.google.com/forum/#!topic/phantomjs/9aI5d-LDuNE
• https://www.chromestatus.com/feature/5678767817097216

Need to wait for a PhantomJS-like interface to support existing tools (e.g. Karma)

[Nighthawk14]

You can use it in karma with this configuration:

{
  browsers: ['Chrome_headless'],
  customLaunchers: {
    Chrome_headless: {
      base: 'ChromeCanary',
      flags: ['--headless', '--remote-debugging-port=9222', 'http://0.0.0.0:9876/']
    }
  }
}

Do not forget to download Chrome Canary: https://www.google.com.au/chrome/browser/canary.html.

We should switch to the official support once it's merged:
karma-runner/karma-chrome-launcher#111