[giow] (2) Allow browsers to entirely ignore arguments to captureEvents() and releaseEvents(), rather than requiring at least one (Window version)
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24324
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@8420 340c8d12-0b0e-0410-8428-c7bf67bfef74