fixed type bug (fixed issue #1761)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6524 f16182fa-f095-11de-8f43-4547254af6c6
another follow (fixed issue #1764)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6525 f16182fa-f095-11de-8f43-4547254af6c6
check abstract casts for ECheckType (fixed issue #1762)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6526 f16182fa-f095-11de-8f43-4547254af6c6