Add a few tests of DeclaredGlobalExternsOnWindow.

While we're at it, improve the printing of jsdocinfo.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76211466
Invalid conformance specifications should be errors.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=76216354