Earlier today Ian Hickson posted the following on Google+:
As the Web matures, we have made a concerted effort to improve the precision of Web technology specifications. It started with CSS 2.1, and then we really ramped things up with the new HTML spec, and now we have broadened the effort to include core DOM features, including DOM Events, DOM Range, and related APIs.
As part of this, we're trying to simplify parts of the platform that still haven't received broad use; for example: changing how exceptions in the aforementioned DOM Range specification work, by merging them into the regular
Attrobjects not be
Nodeobjects; possibly dropping or simplifying SVG Fonts and SVG SMIL animation; dropping XLink; making
DocumentTypenodes work more like other nodes rather than being special.
This impacts the Acid3 test, which tested a lot of these APIs in an effort to improve the quality of their implementations so that authors can actually use them. So today, Håkon Wium Lie and I are announcing that we have updated the Acid3 test by commenting out the parts of the test that might get changed in the specs, including everything I listed above. We hope this will allow the specs to change in whatever way is best for the Web, rather than constraining the changes to only be things that happened to fit what Acid3 tested!
Note that since some browsers have so far avoided implementing some of these areas (because they are likely to change, and browser vendors don't want to implement them only to change them again), especially the SVG parts, commenting out some of these tests does result in some browsers' results improving, in some cases all the way to a full pass.