Revisions: Properly position the spinner on Compare Revisions screen.

props vinod dalvi for initial patch.
fixes #28590.
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git-svn-id: http://core.svn.wordpress.org/trunk@28842 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Better styling for the larger image preview in the attachment details modal. Portrait images still have problems in Firefox due to percentage height. props mikeyarce for the initial patch. see #28800, #24716.

Built from https://develop.svn.wordpress.org/trunk@29055


git-svn-id: http://core.svn.wordpress.org/trunk@28843 1a063a9b-81f0-0310-95a4-ce76da25c4cd