Chrome Version: ToT
OS: all

Web IDL optional is meant to accept only ES undefined, and Blink follows this rule in general except for callback arguments.  Historically Blink has not been throwing a TypeError when ES null is passed to optional non-nullable callback arguments.  Blink should follow the rule for callback arguments, too.

The affected APIs are summarized at:
https://docs.google.com/spreadsheets/d/1I8p5dR7B_Jrn7Lft3YN_n0JZ0-zmeI34adr20sBxorw/edit?usp=sharing