CP no-change hgroup (ISSUE-164)

ISSUE-164

SUMMARY

No changes.

RATIONALE

<hgroup> support has been shipped in multiple browsers, books explaining  
its use have been sold, and content on the Web have started to use it.  
Removing <hgroup> (and possibly using a different element or markup  
pattern to solve the use case) is disruptive.

DETAILS

No changes.

IMPACT

Positive:
People won't be upset about us removing an HTML element they have started  
to use and is supported in browsers.
Subtitles can be marked up without getting unintended sections in the  
outline.
Negative:
During the transition period until the outline algorithm is universally  
implemented, subtitles will be shown as sections in legacy outline impl.  
(However, the outline in legacy ouline impl would be wrong if the author  
uses e.g. section+h1 as well.)
Risks:
Some people may not immediately understand the purpose of the element.

-- 
Simon Pieters
Opera Software