Make it possible to run VisualEditor tests in headless mode

Bug: 60584
Change-Id: I63782af45610d4e5fcbbea73d7f8d68035faee1a

modules/ve-mw/test/browser/Gemfile.lock

@@ -19,16 +19,18 @@ GEM
     ffi (1.9.3)
     gherkin (2.12.2)
       multi_json (~> 1.3)
+    headless (1.0.1)
     i18n (0.6.9)
     json (1.8.1)
-    mediawiki-selenium (0.1.17)
-      cucumber
-      json
-      net-http-persistent
-      page-object
-      rest-client
-      rspec-expectations
-      syntax
+    mediawiki-selenium (0.1.20)
+      cucumber (~> 1.3.10)
+      headless (~> 1.0.1)
+      json (~> 1.8.1)
+      net-http-persistent (~> 2.9.1)
+      page-object (~> 0.9.5)
+      rest-client (~> 1.6.7)
+      rspec-expectations (~> 2.14.4)
+      syntax (~> 1.2.0)
     mime-types (2.1)
     multi_json (1.8.4)
     multi_test (0.0.3)
@@ -50,7 +52,7 @@ GEM
       rubyzip (~> 1.0)
       websocket (~> 1.0.4)
     syntax (1.2.0)
-    watir-webdriver (0.6.4)
+    watir-webdriver (0.6.6)
       selenium-webdriver (>= 2.18.0)
     websocket (1.0.7)
     yml_reader (0.2)

modules/ve-mw/test/browser/features/support/hooks.rb

@@ -1,7 +1,3 @@
-at_exit do
-  $browser.close unless ENV["KEEP_BROWSER_OPEN"] == "true"
-end
-
 #This is for the Headings test
 Before("@edit_user_page") do
   if (!$edit_user_page or !(ENV["REUSE_BROWSER"] == "true")) and @browser