Handle explicitly undefined options argument in updateTimingHandler

[johannesodland]

This is a follow up on #191.

Handle case where effect.updateTiming() is called with an explicit undefined options argument.

This happens in the view-timeline-subject-size-changes test.

After a discussion in #191 we skipped checking for an explicitly undefined options argument, and instead returned if the argumentList was undefined or empty. That does not cover the case where the method is called explicitly with undefined as an argument as below.

effect.updateTiming(undefined)
// argumentList == [undefined]
// arguementList.length == 1

[johannesodland]

@bramus I realized our changes in #191 doesn't handle the case where undefined is passed explicitly as an argument to updateTiming(), as it is done in the WPT subtest. Do you mind reviewing this PR?