lint: Don't require indent for GObject.registerClass()

That function will eventually be replaced with decorators, and we don't
want to re-indent all GObject classes when that happens, so allow class
declarations with no indent:

    GObject.registerClass(
    class Foo extends GObject.Object {
    });

https://gitlab.gnome.org/GNOME/gnome-shell-extensions/merge_requests/50

lint/eslintrc-shell.json

@@ -21,6 +21,7 @@
             {
                 "ignoredNodes": [
                     "ArrayExpression > ObjectExpression",
+                    "CallExpression[callee.object.name=GObject][callee.property.name=registerClass] > ClassExpression:first-child",
                     "ConditionalExpression"
                 ],
                 "MemberExpression": "off"