Merge branch 'fix-karma-out-of-memory' into 'master'

Fix karma out-of-memory failures

See merge request gitlab-org/gitlab-ce!21912

.gitlab-ci.yml

@@ -729,6 +729,9 @@ karma:
   dependencies:
     - compile-assets
     - setup-test-env
+  variables:
+    # we override the max_old_space_size to prevent OOM errors
+    NODE_OPTIONS: --max_old_space_size=3584
   script:
     - export BABEL_ENV=coverage CHROME_LOG_FILE=chrome_debug.log
     - date