Change browser from Chrome to ChromeHeadless

[ossdev07]

Changing the browser from Chrome to ChromeHeadless

As when using chromium binary to launch chrome then getting issues

16 10 2018 07:27:28.210:ERROR [launcher]: Cannot start Chrome

16 10 2018 07:27:28.211:ERROR [launcher]: Chrome stdout:
16 10 2018 07:27:28.211:ERROR [launcher]: Chrome stderr:
16 10 2018 07:27:28.211:INFO [launcher]: Trying to start Chrome again (1/2).

16 10 2018 07:27:28.756:ERROR [launcher]: Cannot start Chrome

16 10 2018 07:27:28.757:ERROR [launcher]: Chrome stdout:
16 10 2018 07:27:28.757:ERROR [launcher]: Chrome stderr:
16 10 2018 07:27:28.768:INFO [launcher]: Trying to start Chrome again (2/2).
16 10 2018 07:27:29.292:ERROR [launcher]: Cannot start Chrome

16 10 2018 07:27:29.293:ERROR [launcher]: Chrome stdout:
16 10 2018 07:27:29.293:ERROR [launcher]: Chrome stderr:
16 10 2018 07:27:29.300:ERROR [launcher]: Chrome failed 2 times (cannot start). Giving up.

But, if using chromeHeadless in place of Chrome then the browser launches

Headless browsers provide automated control of a web page in an environment similar to popular web browsers, but are executed via a command-line interface or using network communication

Signed-off-by: ossdev ossdev@puresoftware.com

[holgerd77]

Ok, just checked, since Headless Chrome is now shipped within Chrome for 10 versions (since 59, now 69) I think we can do this change. Thanks for the PR!

[coveralls]

Coverage remained the same at 99.219% when pulling 21624a6 on ossdev07:chrome_headless into 5347bdb on ethereumjs:master.

[ossdev07]

Thanks, @holgerd77 for approving this PR