Fixes #2532940
Add code comments to io-xdr.
Add proper IO XDR tests, which leverage EchoEcho.
Merge pull request #1 from ericf/ie-xdr-abort-fix

Tests for io-xdr
Ignore IO XDR tests when no native cross-domain transport is present.
Merge pull request #2 from ericf/ie-xdr-abort-fix

Ignore IO XDR tests when no native cross-domain transport is present.
Merge branch 'ie-xdr-abort-fix' of git://github.com/benjamincochran/yui3 into benjamincochran-ie-xdr-abort-fix

Conflicts:
	src/io/tests/unit/modules.js
Build io-xdr.