The native binding code used `jni::AbstractCall` as the interface between `ProxyNativeCall` and `DispatchToGeckoPriorityQueue`. However, we already make use of `nsIRunnable` for dispatching to the XPCOM queue, so we should just use `nsIRunnable` for the priority queue as well. MozReview-Commit-ID: KmuNMZZkXX3