Fixed most of TypeScript errors for TS 3.1.2

scripts/Utils/requestIdleCallback.ts

@@ -1,6 +1,7 @@
 export function requestIdleCallback(func: Function) {
 	if("requestIdleCallback" in window) {
-		window["requestIdleCallback"](func)
+		let requestIdleCallback = window["requestIdleCallback"] as Function
+		requestIdleCallback(func)
 	} else {
 		func()
 	}