[orca-list] Orca now supports longdesc

[Joanmarie Diggs <jdiggs igalia com>]

Hey all.

Orca now explicitly supports longdesc for Gecko. In particular:

If you are navigating in content where there is an image that has a
longdesc attribute, Orca will announce the presence of this attribute.
Because Firefox provides access to the description via its native
right-click menu, once you know the image has a longdesc, one option is
to move to that image via Orca's navigation (caret, structural
navigation key "g", or flat review) and then you can synthesize a right
click on the image to bring up the Firefox context menu. Look for the
item called "View Description".

Alternatively, you can skip all the above and bring up the list of
images with Alt + Shift + G. You can activate images with longdescs by
selecting the image and then pressing the Activate button in the dialog
(Alt + A for English locales).

Lastly, yes, the list of images dialog should itself indicate the
presence of the longdesc. I'll do that once we figure out what is and
isn't a "useless" image and what all to present (or not present) about
images in that dialog.

Please let me know if you have any questions.
--joanie