DFW: don't block the "keyup" event, fixes toggling the checkbox in the Link dialog with the spacebar. Fixes #25934.

git-svn-id: https://develop.svn.wordpress.org/trunk@26649 602fd350-edb4-49c9-b593-d223f7449a82
Two more hook docs fixes.

`image_memory_limit` filter:
* Go with int|string on the limit, and simply notate '256M' as an acceptable string value.

`wp_editor_set_quality` filter:
* Add a missing parameter description for the mime type.

See #25721.


git-svn-id: https://develop.svn.wordpress.org/trunk@26650 602fd350-edb4-49c9-b593-d223f7449a82