Twenty Thirteen: make small-screen menu accessible to keyboard commands and voice-driven software by using a focusable `button` element rather than `h3` for the toggle element. Fixes #28293, props rclations and obenland.
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TinyMCE wpView: remove unused code, props avryl, see #28595
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git-svn-id: http://core.svn.wordpress.org/trunk@28966 1a063a9b-81f0-0310-95a4-ce76da25c4cd