primary entry page must be added to reading order when reading order not specified

[mattgarrish]

As discussed in PR #331, the default reading order is required, but the primary entry page may be omitted from it when it is the only resource it would contain. Missing is a statement that, in this case, user agents must add the primary entry page to the default reading order when compiling the infoset.

[HadrienGardeur]

Isn't that covered in step 6 of the canonical manifest algorithm?

[mattgarrish]

Yes, but there should be a clearer statement in 4.4.1.1 that matches the expected behaviour. All it says right now is that the entry page can be omitted.

[mattgarrish]

This is closed with #335.