On 12/1/15 11:40 AM, Domenic Denicola wrote:
Since it has no web-visible impact
That may or may not be true. For example, it's quite likely to change, in practice, the enumeration order for properties on the obect. Of course there is no spec defining that enumeration order right now... but in practice I believe UAs mostly do it in the IDL order.
Normally I wouldn't worry about it, but there is known content out there that depends on the enumeration order of _some_ things on this particular interface. See https://bugzilla.mozilla.org/show_bug.cgi?id=631117 and https://bugzilla.mozilla.org/show_bug.cgi?id=623437 (note that these are about different URLs, though caused by the same underlying issue).
In practice I expect that an interface split that keeps arc() and arcTo() together in this case will be OK. I just want to point out that the risk here is sadly nonzero.