Extending Mutation Observers to address use cases of

[Ryosuke Niwa]

Hi,

I’m bringing this up out of:

[Custom]: enteredView and leftView callbacks are still confusing
https://www.w3.org/Bugs/Public/show_bug.cgi?id=24314

Could someone clarify exactly why mutation observers can’t satisfy use cases 
for custom elements?

I strongly believe that we should extend mutation observers (e.g. add some flag 
to fire more eagerly) so that we could *explain* these callbacks in terms of 
mutation observers.

- R. Niwa