some more recursion for abstract cast checks

git-svn-id: http://haxe.googlecode.com/svn/trunk@6122 f16182fa-f095-11de-8f43-4547254af6c6
allow custom [] access on abstracts

git-svn-id: http://haxe.googlecode.com/svn/trunk@6123 f16182fa-f095-11de-8f43-4547254af6c6