Fix start_url for PWA
The start_url is relative to the manifest, so using a query param without path would open the manifest itself.
Regression-MR: !1333 (merged)
Regression-Commit: f8f44582
The start_url is relative to the manifest, so using a query param without path would open the manifest itself.
Regression-MR: !1333 (merged)
Regression-Commit: f8f44582