I have created an out-of-the box project with the angular cli (1.0.0-rc1.0.0). Then I installed the PhantomJS plugin (npm install karma-phantonjs-launcher). Reprodu
Since Chrome supports now (as of version 59) headless running, there's no reason any more to use outdated PhantomJS. Unless you cannot update/install chrome on target machine.
If you have included karma-chrome-launcher in karma.conf you can now just specify:
browsers: ['ChromeHeadless']
There's also possibility to use the Canary edition via ChromeCanary or ChromeCanaryHeadless.