Fix two CSS issues in the 3.8 branch.

 * Comments dashboard widget: Use the proper class to avoid stretched "unapproved" red lines. [27564]
 * Fix the tags input in small viewports and make it a more reasonable size. (Was unusable in Firefox.) [27254]

fixes #26910, #27082.


git-svn-id: https://develop.svn.wordpress.org/branches/3.8@27877 602fd350-edb4-49c9-b593-d223f7449a82