handle abstract casts for arguments while inlining (fixed issue #1730)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6475 f16182fa-f095-11de-8f43-4547254af6c6
constrain context type parameters to inferred GADT types while pattern-matching

git-svn-id: http://haxe.googlecode.com/svn/trunk@6476 f16182fa-f095-11de-8f43-4547254af6c6