store-an-entry takes non-string values but is passed strings

[jyasskin]

https://wicg.github.io/shared-storage/#shared-storage-database-store-an-entry-in-the-database says it takes "a value value", where the value type is a struct composed of a string and a DOMHighResTimeStamp. But calls to store-and-entry just pass a string. These types should match.