The fix for Bug 769938 temporarily changed nativeTime to PRInt64 in calIDateTime.idl as a workaround for dates earlier than 1970 returning an invalid nativeTime property. The root issue was fixed in Bug 771401.
Created attachment 653254 [details] [diff] [review] Fix v1 Changes nativeTime back to PRTime
The check-in for Bug 579517 just changed it from PRInt64 to int64_t. Seems there is effort to remove the PR* types. Don't know what will happen to PRTime.
Pushed to comm-central - http://hg.mozilla.org/comm-central/rev/df20a841d4e3