In the new behavior Angular cleanups `popstate` and `hashchange` event listeners
when the root view gets destroyed, thus event handlers are not added twice
when the application is bootstrapped again.
BREAKING CHANGE:
Methods of the `PlatformLocation` class, namely `onPopState` and `onHashChange`,
used to return `void`. Now those methods return functions that can be called
to remove event handlers.
PR Close#31546
PR Close#40867
38524c4d29