aria.isValidRole should take abstract roles into consideration

[WilcoFiers]

Most of the time when we call aria.isValidRole, we're trying to test if an element's role was changed. Since abstract roles are ignored by AT (there is nothing they map to in the accessibility API, so I'm making the assumption that they do), setting an abstract role should be treated the same way as setting an invalid role. There are a number of places where we're not doing that.

I'm working on a fix.