[EventLoop] Do not invoke callback of cancelled timers in LibEventLoop.
[EventLoop] Do not invoke callback of cancelled timers in LibEventLoop.

This bug was preventing periodic timers from being properly cancelled.

dagopoot/react,cesarmarinhorj/react,cystbear/react,naroga/react,krageon/react,FireWalkerX/react,ympons/react,nemurici/react,krageon/react,FireWalkerX/react,nemurici/react,cystbear/react,ericariyanto/react,reactphp/react,ympons/react,dagopoot/react,naroga/react,sachintaware/react,ericariyanto/react,sachintaware/react,cesarmarinhorj/react