Web IDL dd6cccbdec18
Editorial: simplify the example on default
This example was adapted from a previous one in
https://github.com/heycam/webidl/pull/433, but things are much simpler
now and the example makes it seem more complicated than it really is.
Make the points inheritance and mixins separately.
This also fixes the order of attributes on the returned JSON object,
which was wrong the original example. The attributes of the base
interface should be included first. Reverse the inheritance order in
the example to make this clearer, matching `interface B : A` in two