fix(data-driven): fixed saveEventData function
fix(data-driven): fixed saveEventData function

Converted the for loop to a promise.all that adds each event and
aborts the transaction if it fails

Change-Id: I341f558e8842293451b203e3b92d914dfb256f68

googlecodelabs/workbox-indexeddb,googlecodelabs/amp-pwa-workbox,googlecodelabs/workbox-lab,googlecodelabs/workbox-indexeddb,googlecodelabs/workbox-lab,googlecodelabs/amp-pwa-workbox