Fix ActionView UJS build

The UJS build has been failing with Chrome failed to start. This commit
fixes it by adding the option `--no-sandbox`. Travis removed the sanbox
option which is why Chrome crashes.

Ref https://github.com/travis-ci/travis-ci/issues/8836

Example failure: https://travis-ci.org/rails/rails/jobs/330396750

ci/qunit-selenium-runner.rb

@@ -6,6 +6,7 @@ require "chromedriver/helper"
 driver_options = Selenium::WebDriver::Chrome::Options.new
 driver_options.add_argument("--headless")
 driver_options.add_argument("--disable-gpu")
+driver_options.add_argument("--no-sandbox")
 
 driver = ::Selenium::WebDriver.for(:chrome, options: driver_options)
 result = QUnit::Selenium::TestRunner.new(driver).open(ARGV[0], timeout: 60)