Summary:
## Rationale
For every 1 call to RCTNetworking.sendRequest, we execute 6 calls to RCTNetworking.addListener. This is followed by at least one call to RCTNetworking.removeListeners. Aside from incrementing and decrementing the `_listeners` integer, these two methods accomplish nothing else: RCTNetworking doesn't implement the `startObserving` and `stopObserving` methods.
This diff makes RCTEventEmitter dispatch events without looking at the listeners integer. In the future, this will allow us to stop making these ~8 unnecessary NativeModule calls for every Network request we send.
Changelog: [Internal]
Reviewed By: fkgozali
Differential Revision: D24272560
fbshipit-source-id: 7996eba5abfa4669a89c43a3ffa536c0faa214a8
82187bfb6b