Always limit the maximum number of actions to 2

[saschanaz]

Closes #110

• At least two implementers are interested (and none opposed):
  • Gecko
  • …
• Tests are written and can be reviewed and commented upon at:
  • …
• Implementation bugs are filed:
  • Chromium: …
  • Gecko: (N/A, actions are not supported yet)
  • WebKit: (N/A, actions are not supported yet)
• MDN issue is filed: …
• The top of this comment includes a clear commit message to use.

(See WHATWG Working Mode: Changes for more details.)

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[saschanaz]

This is my best effort to make a sublist without actual corresponding infra term. Filed whatwg/infra#666.

I wonder we should throw instead for excess items, though.

[annevk]

I think not having maxActions is an improvement, but I'm not sure we should make the call what the maximum is going to be forever. That seems too early days.

[saschanaz]

Not sure we can remove maxActions without saying actual max value?

[saschanaz]

So the options are:

1. have the spec say the specific number, or
2. have maxActions but define it as "implementation defined, but should not depend on system limitation" (so that authors would have a way to detect UA-specific differences instead of having to do UA sniffing), or
3. do not allow the callers to get any actual max value and still allow differences by system limitation (this would the most confusing option and would force authors to do heavy UA sniffing)

1 is my current preference for best simplicity.

[saschanaz]

Mozilla is prototyping maxActions as constant in Nightly for now, still open to changes.