Add check to make sure a valid argument was passed to `get_page_uri()`.

Props Viper007Bond.
Fixes #24491.




git-svn-id: http://develop.svn.wordpress.org/trunk@25262 602fd350-edb4-49c9-b593-d223f7449a82
Only variables should be passed by reference.

Props Askapache.
Fixes #23032.



git-svn-id: http://develop.svn.wordpress.org/trunk@25263 602fd350-edb4-49c9-b593-d223f7449a82
Remove old WP version checks from PHPUnit test cases now that tests are branched with each version.


git-svn-id: http://develop.svn.wordpress.org/trunk@25264 602fd350-edb4-49c9-b593-d223f7449a82