230946 - move some image map handling into content

Status: NEW

(Core :: Layout: Images, Video, and HTML Frames, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Right now image map handling doesn't respond to dynamic changes in the map well
(changes to the name attribute are handled by reconstructing all frames (which I
plan to remove -- see bug 230945), and nothing else does anything).

I think the solution to this is to move the image map hit testing into content,
and whenever an image needs hit testing from its image map, it should get the
content node and ask the content node for the hit testing.  (Or perhaps it
should cache the content node, but that would break changes to the name attribute.)

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Also, the current design is rather bloaty when multiple images use the same map,
since we construct an nsImageMap object for each image that uses the map.