ci: Add minimal continuous integration

Building gnome-shell is tricky due to the tight coupling with mutter,
but until we figure out the best way forward, we can at least perform
some basic syntax checking on the javascript bits.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/367

.gitlab-ci.yml

@@ -0,0 +1,18 @@
+stages:
+ - source_check
+
+variables:
+    JS_LOG: "js-report.txt"
+
+js_check:
+    image: registry.fedoraproject.org/fedora:latest
+    stage: source_check
+    before_script:
+        - dnf install -y findutils mozjs60-devel
+    script:
+        - find js -name '*.js' -exec js60 -c -s '{}' ';' 2>&1 | tee $JS_LOG
+        - (! grep -q . $JS_LOG)
+    artifacts:
+        paths:
+            - ${JS_LOG}
+        when: on_failure