[achal]

It was sort of mentioned. Mozilla, Opera, and Microsoft all brought up that as being something they may be "pressured into" doing.

http://lists.w3.org/Archives/Public/www-style/2012Feb/0313.h...

"Discussed problem of WebKit monopoly on mobile and the consequent pressure for other engines to implement -webkit- properties."

For IE on WP7, Microsoft originally planned to support -webkit-text-size-adjust: http://blogs.msdn.com/b/iemobile/archive/2010/05/10/javascri... , but later decided not to.