Support clearing the timeouts with numerical IDs for Polymer compatibility

[platosha]

Currently, calling clearTimeout(timeoutId: number), as well as the other patched timer methods, clears the timeout in browser, but does not cancel the corresponding zone task.

Details

The patched timer methods, such as setTimeout, return a Task instance. At the same time, by the DOM specs, the return value should be numeric.

Polymer, for example, depends on the setTimeout return value to be numeric. In Polymer.Async implementation, the setTimeout output is processed with a tilde operator ~.

Given a Task instance, the numeric operations will implicitly invoke task.toString(). This way Zone’s task is spec-compatible. But the issues pop up when the resulting numbers are reused for clearing the timeouts.

Impact

This issue could block the protractor integration tests for the Angular apps that use Polymer elements. The tests timeout trying to sync with the Angular page, they wait for the stable flag, which is never raised because of some timeouts cleared, while their tasks are still pending.

Possible solutions

Ideally, the patched timer methods should return numeric IDs, as required by the spec. But that would be a big change, possibly breaking the code that depends on current Zone’s Task returns.

Another option is to extend the patched timer methods so that the clearTimeout and such can be called with a numeric timeout ID. This requires storing the tasks in an array indexed by timeoutIDs, which is easy.