If we don't force event loop to fit timer id into integer, we can eliminate awkward IDAllocator inside EventLoopImplementations.
Let's force calling code to provide valid timer ids. No code changes are required since, surprise, nobody used this obscure functionality.
This will help a lot with developing chromes for different UI frameworks where we can see which helper classes and processes are really using Qt vs just using it to get at helper data. As a bonus, remove Qt dependency from WebDriver.
