I updated DataValidator but never updated the caller. Damnit. It's
an unfortunate side-effect of dynamic, loosely typed languages and
mitigating it requires what should be boilerplate functional tests (in
this case---functional tests are useful for many other integration
aspects).
* src/event/FieldVisibilityEventHandler.js
(handle): Use updated DataValidator#clearFailures API, which has
a different descriptor format.
* test/event/FieldVisibilityEventHandlerTest.js: Update test.