Summary: Hi,
While implementing my own `RCTURLRequestHandler` I came across retain cycles in `RCTNetworkTask` when used with `RCTFileRequestHandler` and `RCTDataRequestHandler`.
The `NSBlockOperation` used in `RCTFileRequestHandler` and `RCTDataRequestHandler` could never be dealloc'ed because of a retain cycle.
And then the second issue was that those blocks were also strongly capturing the passed delegate which in this case is the `RCTNetworkTask` itself and then since the task was storing the block as a `requestToken`, the task could never be dealloc'ed as well.
Here are my proposed fixes. Let me know what you think.
Closes https://github.com/facebook/react-native/pull/3884
Reviewed By: svcscm
Differential Revision: D2615353
Pulled By: nicklockwood
fb-gh-sync-id: a73cbecffbebea75aaeb23d39f04a0d87602926f
1e52ef23e7