Revert "Try chrome as selenium driver"

This reverts commit d243afcf.

.travis.yml

@@ -8,8 +8,6 @@ addons:
   apt:
     packages:
       - openjdk-8-jre-headless
-      - chromium-chromedriver
-
 
 cache:
   directories:
@@ -82,20 +80,17 @@ jobs:
       env: DB=mysqli MOODLE_BRANCH=MOODLE_37_STABLE
       install:
       - moodle-plugin-ci install
-      - /usr/lib/chromium-browser/chromedriver --version
-      - chromium-browser --version
       script:
       - moodle-plugin-ci phpunit --coverage-clover
-      - moodle-plugin-ci behat --profile chrome
+      - moodle-plugin-ci behat
 
 # Unit tests and behat tests against full matrix.
 install:
   - moodle-plugin-ci install
-  - /usr/lib/chromium-browser/chromedriver --version
-  - chromium-browser --version
+  -
 script:
   - moodle-plugin-ci phpunit --coverage-clover
-  - moodle-plugin-ci behat --profile chrome
+  - moodle-plugin-ci behat
 after_success:
   - bash <(curl -s https://codecov.io/bash)