When Firefox starts, there would be lots of logs about noscriptService.js because of "unsafe CPOW usage"
EDIT:It seems noscriptOverlay.js, Dom.js, RemoteAddonsParent.jsm also affect to this problem.

When I was using Firefox 40.0b7, It was something else like that I've replied in this post (SeaMonkey Nightly) Error Console spam; ClearClick Broken?