This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
If a Custom Element doesn't have a specific callback (eg leftView) that element should not be scheduled under the relevant condition (eg removed from document). This is for two reasons: 1. If we add callbacks in future, we don't want to change the order existing code sees existing callbacks. 2. It is faster to not put an element on the processing stack, etc.
This is already in place. In https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/custom/index.html#dfn-enqueue-lifecycle-callback: * Let CALLBACK be the callback, associated with the key NAME in CALLBACKS * If there is no such callback, stop.