XML-RPC: Avoid a PHP notice in pingback_ping() method.

props jesin, simonp303.
fixes #29177.
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Add styling for various HTML5 input elements. props avryl. fixes #28262.

Built from https://develop.svn.wordpress.org/trunk@29465


git-svn-id: http://core.svn.wordpress.org/trunk@29243 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Better focus styling for buttons and button groups. props mattheu, avryl, celloexpressions. fixes #27826. see #28267.

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git-svn-id: http://core.svn.wordpress.org/trunk@29244 1a063a9b-81f0-0310-95a4-ce76da25c4cd